Dead Space was in development for a long while before EA ever made the "PS3 is our lead" announcement.  They may have switched mid-development cycle, or any number of things.

Any number of reasons could be the reason why you think it looks worse on the PS3.  Perhaps the shaders are significantly different, and the X360 shader guys were brighter than the PS3 shader guys.  Perhaps the normal maps are reduced or missing on the PS3 version, because DS had big textures, and the team didn't put the time into researching what cool dynamic lighting could do for them, so they resorted to relying upon as much texturing as possible (a perfectly valid art decision -- but not one that would necessarily suit both the 360 and PS3 well), etc. etc.

How games loo k is entirely dependant on the teams that make them, and their design decisions.  Because one team decides they want to pursue a model that fits the 360 better than the PS3, has no bearing on the potential looks, or performance, of other games, made by other teams.  Dead Space was in development for a long while -- well before most engineering teams really understood the best models to develop on both platforms concurrently would look like.  Answering your question won't provide the answers you're looking for.

If I am not mistaken Dead Space was developed on the PS3.

I wasn't talking about going multi-platform in general, but in the specific case of Mass Effect...and the possible benefits, or lack there of in possibly going back to release the original game on the ps3, while keeping in mind the weak performance of Bioshock, which 2kGames invested some serious effort into.  Is it worth delaying the game's release during the holiday season to multi-platform it?!?  I doubt it, and that's also part of my point...going multi-platform would require you possibly getting a far larger team (as Procrastinto and Sqill pointed out), and that 10% added cost is probably after you have optimized your processes, not at start-up.  Now EA could farm it out to someone else to do, since Bioware is also busy working on Dragon Age which is going to be multi, as far as I know, but then that just adds more cost.  So, I DID think about it before I posted, and hope that clarifies my point.

@Procrastinato:

Dead Space was lead on the Xbox 360 with 'extra effort' given to the PS3.

The reason why I suggested the Xbox 360 SDK as better is because with the PS3 programmers have to do too much manually, in terms of balancing the load to make everything work and tweaking low level code. Furthermore the programmers who specialised in working on the Cell earn/earnt a premium when the push came through to bring the PS3/Xbox 360 versions up to par. Lastly we have comments by people such as Carmack who stated he had to put his best programmers on the PS3 version to bring it up to par with the Xbox 360 version which was designed relatively seperately as far as I can tell.

The only games I know of which were designed with seperate programming teams for the Xbox 360 and PS3 versions are GTA IV and COD IV and both examples actually gave the Xbox 360 better overall performance compared to the PS3 versions without being ported from that architecture and without potentially gimping the PS3 version with a sub par port of code.

@ Squilliam

I hear what you're saying, I think. All the examples you're giving sound like support for the "dev on the PS3 first" argument, though. Clearly lots of teams have trouble porting engines designed for the 360 over to the PS3, as you state. Anecdotal evidence from early 360->PS3 ports demonstrates this pretty well, I think.

I think EA's future games -- I think game such Madden '10 may be the first such example -- will show the benefits, in terms of performance, from their "develop on the PS3 first" decision. That decision's effects won't have seen the light of day/the store shelf, just yet.

EA also has a special "need" they want to address, due to their heavy-hitting sports franchises -- they have exactly the kinds of products that stand to benefit hugely from extremely complex character skeletons and animation, performed on large numbers of onscreen characters. That's a prime candidate for large-scale CPU parallelism -- I would even say its the prime candidate.

The PS3 has huge potential in that area, and I would not be surprised if the lead engineers behind those projects realized that, by redesigning their engine(s) around the parallel concepts that the PS3 excels at, they could achieve better performance on the X360 than their current/older engine gave them, and downright stellar PS3 performance for that part of the game frame. Good animation is critical to good-looking sports titles -- the more bones in the animated skeleton, the better, the higher sample-rate, the better, the more blended animations... better. Qu ality animations are critically important for the future of EA's sports franchises -- and they aren't going to skimp on them, when their competition may up the bar.

In this regard, EA is different from most developers -- they have a bar to reach, and compete at, with regards to performance.  Shortening development time and cost on their sports franchises is much less important to them, overall, than beating the competiton is, since most of the expense on these titles is actually not the engineering dev costs.  

Other types of games don't stand to benefit as much from the performance gains yielded by this decision, and in many cases, the extra dev costs may not be worth the trouble.

As far as EA Sports is concerned, however, I would say that the extra dev costs are most certainly worth it.  If they share internal engine technology, then they may as well apply that dictum across the board -- and they have done so.

So if I'm understanding you correctly, the team that originally worked on the PS3 design, would hten be the team to port over the game to the 360?  Therefore, requiring the design team to be versed in both platforms?  I'm not sure if this is how it's already done or not, and logic would seem to indicate that if you could find enough people skilled to work expertly on both, you'd seriously have a win-win situation...but I'm not sure?  I'd be really interested to so the cost breakdown on that 10% rough order of magnitude on going multip-platform.  It is still a sizable $$$ amount on a 420-30 million project, but it's better than 50-60% more.

I am now out of my depth, I cannot argue any further.