that's very nearly what they do. It's a little more complicated because it sets a "singularity" at a height that pulls you in towards it to deal with fluctuations, i.e. you don't fall out of it by shifting 1m up or down. The issue becomes when you move that singularity. The implementation is that it changes altitude very slowly so it's not supposed to be a good way to gain altitude, just park.
even if agg could be used all the way to the ground, or worked as a hard altitude lock, there is still incentive to have 1km towers. You want to never have to move your singularity height if you don't have to, and you want the singularity to be set as high as you can go and still be able to access your linked container (high enough to avoid low obstacles like terrain and random constructs around markets.)
I really don't know what the solution is. I don't think lowering the height will change tower density or height. Raising the height might reduce density a little bit but I wouldn't count on it. Maximum build height might be a potential route, but would you use height above terrain or above 0? And what if you dig out some terrain, or build up some terrain?
My instinct is the solution would be limiting number of static cores on a tile the closer you get to the districts or a market, so if you want to build something big, it also has to be remote.