Meh, most good games now are switching over to the two-disk system. The last three I bought (BF3, Forza 4, Halo 4) all had two disks, so I imagine that with the amount of content they are promising GTA V will be no different.
As for hard drive space, you really do need to get the larger drives. Yea it's a pain that they aren't included from the start, but it's just something you have to live with.