Unless Sony takes a stance iself devs are going to use the HDD. It's too tempting. Look up devs quietly moaning about lack of HDD on 360. If 360 had an HDD and MS did not mandate no installs you'd be installing just as much on that console too.
HDD install makes life easier for devs to get certain load times, etc. I suspect that most games on PS3 with installs could have had them cut but this would have taken additional development cost and effort (remember on 360 they have no choice but to make it work) and I figure a lot of devs just take the easy route.
It's no good pointing to BR speeds or the like as there are plenty of decent games such as Uncharted or R&C that seem to have very minor to no install and its completely transparent - all its takes is one proof point to show it can be done : but without pressure a lot of devs will use HDD anyway.
At least Sony used standard HDD so putting in more space is easy (I'm currently working with 250GB for example).
Oh, and would I prefer no installs - sure, in principle, although I don't mind if it boosts performance rather than serves as an easy out on further costs for devs.
Try to be reasonable... its easier than you think...
