I don't think that's right. Getting a bit more technical, we're talking about Layer 2 (for the VLANs) vs. Layer 3 (for the router) of the OSI model. Of course, inter-VLAN routing is handled at Layer 3 via a router or Layer 3-capable switch, but that makes complete sense given you're talking about inter-VLAN routing. To put it more simply, though, VLANs segment a given network into separate, virtual networks (and, yes, prevent one network from "seeing" or interacting with the other without explicit permission to do so). But the router should absolutely still be aware of and faithfully report all network activity, including clients connected to it and the traffic it's processing. And that's what I'm saying is lacking in the GL.iNet UI. Right now, the GL.iNet UI is telling me the router has zero connected clients, which is flat out wrong. The existence of VLANs or an entirely flat network shouldn't factor into the fidelity of the router's reporting of client connections. And as a case-in-point, LuCI dutifully reports all client connections in one UI, irrespective of the VLAN to which the client is connected. Adding UI support for this on the GL.iNet side of things would (or should) have no bearing on the utility of VLANs.
I don't think this is beyond typical home users. Perhaps that's a matter of / difference of opinion, and that's totally fine. But running VLANs seems very much within typical home use. It's an extremely common way of setting up guest networks or segmenting IOT devices, for example.
50 VLANs is ... aggressive. I agree with you there for sure. 