Too slow, too weak, too inefficient, too much backlash, not backdrivable, no energy regeneration, no built in force sensing.

Add sloppy controls to the list.

It's not that rc-servos are not sexy. It't that they suck. For a number of specific reasons well listed in other posts here.

RC-servos are very cheap and very easy to use, so there are many projects using them. But there is no way to make a good robot out of them. It's a local maximum.

All true. But they are cheap, available, and have well understood limitations. Which means you can design and build your project quickly and cheaply, then upgrade to brushless motors with encoders or whatever when you have the time and funds. I think from that aspect they are a great way to get a project started without flinging cash at it.

IMO the only inherent issues with hobby-style servos are lack of feedback (force and position) and lack of direct torque control. The rest of the complaints are features of all cheap positioning elements and aren't unique to hobby servos.