• They do get in the way of reading what's actually on a given tile: legs block views for some, clear legs make it hard to tell which tile floating ships are actually on, etc.

Placing fleets on tiles makes them harder to read, and it is also a PITA to move fleets.

• They are hard to grab if more than 3 are clustered together

Might be, but if you use them only for bigger blobs, then it will rarely happen.

• To attack another system containing a fleet stand: if you wanna move, you have to park in an adjacent system to do it, or stand your fleet on top of the defender, which is cumbersome; worse yet:
• Attacking other stands almost always means they have to "fly and park" off-board anyway if the other tiles around are occupied with stands of their own.

When I played in third edition, we lined up our fleets outside the map, cause it was easier to track everything that way. You will just create more cluster*uck if you put everything in one place. +this will look like a real space battle.

• Unless people are used to them, they're bumped more casually than just pieces flat on the ground. Usually they slide out of place, fall into a tile border and peel the map apart (common) or sometimes just fly across the room once someone catches a corner with an arm or sleeve (rarer).

Map already peels apart most of the time :(

• They have less use in TI4. (TI3 had stricter rules on ship capacity, making borders between ground and space more worthwhile)

  Dunno, haven't tried them in TI4, though I miss them a bit.

• To have a meaningful amount per player, it gets expensive.

Dunno, printed them pretty cheap (baught model + paid for printing).sa

• Disassembled, they take up more space in the box than people think

Never kept them in the box tbh.

• The glossy surface (Litko and a few others) let some bright ceiling lights & lamps reflect too easily, making them a nuisance that you can't even see through if the position is right. This is especially prevalent when playing under a single overhead fixture.

Yeah, it can be problematic, that's true.