The ISS isn't in a particularly good orbit because it's highly inclined (so Russia could easily launch to it) which is an expensive issue to fix dV wise unless

The ISS isn't in a particularly good orbit because it's highly inclined (so Russia could easily launch to it) which is an expensive issue to fix dV wise unless all the target satellites are in a similarly inclined orbit. In terms of making them easy to swap out that's certainly possible but it will add weight compared to a monolithic satellite and so far we have very very little experience building and repairing things in space without using people.