The Reapers had no interest in other galaxies, their mandate was to keep the Milky Way "stable". Protheans were arrogant enough to think they could actually beat the Reapers, they weren't interested in running away. And then they found out they couldn't beat the Reapers, and they came up with a different running away idea, i.e. hibernating in secret; which didn't work

I don't think the "because no one did it before the technology doesn't exist" is a good argument. When you have a lore that includes FTL travel you pretty much have carte blanche for being able to travel at least to other galaxies in the local cluster. 

I don't think there should be a series of Ark ships. There should be one ship that was experimentally designed as an intergalactic voyager, as a joint venture undertaken by all council races, that was going to travel unmanned. But with the Reapers showing up they decided that a manned mission was worth the risk.

See, I don't buy that the Reaper's only wanted to make the Milky Way stable. I think they couldn't go to Andromeda because it is too far away. They, as a AI race, would see no issue in carrying out their goal to other parts of the universe if they could gain access to them. The Milkyway is 100,000 light years across and it took the Mass Relays to travel that distance in a small amount of time (unknown really as we don't have any reference to how long that takes)  once they were put there. But there is no Mass Relay in Andromeda to get to, the travel would be based on FTL (as you suggest) and even if that's twice the speed of light, it would still take over 1 million years to reach Andromeda. Even Star Trek's Warp Speed didn't visit other galaxies and that had races like the Borg in it.

I think the sheer distance is just too great. I do not think technology exists because very few sci-fi genre's have done intergalactic travel.

I can get what you mean though, I do however think based on game programming/character modeling. Doing a single ship of inhabitants of some human/Asari/krogan etc would be a waste of character models as they are the only ones as none of the inhabitants of Andromeda would be like that.

@ bolded

These are complete unknowns. The reapers as an AI race, probably wouldn't care about time so much. They could spend half a cycle getting to Andromeda, harvesting and another half-cycle to return. Having said that, I do think that the reapers only cared about the Milky Way. They were made and designed in the Milky Way and I don't think their goals would stretch further unless they had direct evidence of organic vs synthetic life in a separate galaxy where they had to maintain "balance".

Also, we don't know whether Andromeda has Mass Relays or not. We don't really know enough about the civ that built the Mass Relays and the Reapers to know if they ever reached Andromeda.  

Edit- I do remember vaguely that the survivors rebuild the Mass Relays at the end of Mass Effect 3 so their could lead to a new bit of research to get to Andromeda. I can envisage the game having you setup and build new Mass Relays as you make progress, effectively making you a true "pathfinder".

@ bolded

These are complete unknowns. The reapers as an AI race, probably wouldn't care about time so much. They could spend half a cycle getting to Andromeda, harvesting and another half-cycle to return. Having said that, I do think that the reapers only cared about the Milky Way. They were made and designed in the Milky Way and I don't think their goals would stretch further unless they had direct evidence of organic vs synthetic life in a separate galaxy where they had to maintain "balance".

Also, we don't know whether Andromeda has Mass Relays or not. We don't really know enough about the civ that built the Mass Relays and the Reapers to know if they ever reached Andromeda.  

Edit- I do remember vaguely that the survivors rebuild the Mass Relays at the end of Mass Effect 3 so their could lead to a new bit of research to get to Andromeda. I can envisage the game having you setup and build new Mass Relays as you make progress, effectively making you a true "pathfinder".

I told that to myself about Mass Effect 2 and 3, and thanks God I didn't wait because they still haven't launched them, so...

That is true. They never launched that on PC. Even the trilogy which now goes on sale for 10-15 bucks doesn't include the dlc i think. I played ME2 on ps3 and it came a year late compared to 360 but it was nice having all the dlc on disc. Still haven't played any of the dlc of 3, well kinda didn't want to either.

Well, we don't know if the Protheon did it or not. Maybe they were still travelling when the events of Mass Effect took place.

And the Reapers story has many holes in it, and that is one. If they want to preserve "life" or civilizations by turning them into Reapers, why didn't they go and do that in the other galaxies as well?

We don't know that they didn't. Told as it was from the perspective of the relatively primitive species of the Milky Way, for all we know the Reapers actually spent some portion of their time in neighbouring galaxies carrying out the same activities as in the Milky Way.