They can't make them a little bit bigger? But also I found this interesting image on the scale at hand here of a given launch of starlinks, no clue how many are included in a single launch, and it is a substantial amount of rack space they have been sending up at once:

https://i.redd.it/zh7qvyfqgvx21.jpg

So to me they have solved the issue of having a space based compute array network interfacing with the earth. They have solved the issue of launching and deploying this array. And their given launches seem to have a substantial payload of compute going up at once just in sheer volume. And right now the only real difference is that the nodes they are launching are just pretty weakly specced. Everything else is in place and turnkey.

But most of that is nothing to do with compute. A rack of servers is all compute. Starlink sats are antennas, RF amplifiers, solar panels, laser links, shielding, even maneuvering thrusters and fuel for those (they could be electrical ion thrusters but they'll still need reaction mass, not sure what type they use). Probably some inertial reaction wheels too, they are used for spacecraft orientation, not positioning.

They are sending a few racks of stuff up every launch but the problem is not that it's underspecced. It's that most of it is just needed for equipment survival and communication in space.

You're talking about an environment that's full of radiation and goes from -200C to +200C every 90 minutes. That needs to be orbit managed and cooled (and sometimes also heated) without any airflow. Just sticking a few servers in a barrel isn't going to do the job.

So if they send up a starship with a hypothetical "compute rack", you wouldn't need all the redundant antennas, rf amplifiers, discrete solar panels, etc. You'd need just one of each sufficient for the whole rack, rest can be compute.