Having more technologies that unlock as you up Science Museum would give Guilds a reason to upgrade it... as it is, as MisChief said there's not much reason to go past lv 4. With the high rate of increase in the game comparable to level, especially the higher levels, the extra techs would help out a lot in the long run. And argument that it would throw off balance is negatable at best, as this actually would work to even out some of the OP issues for lower and mid level players.