The value in the ability to upgrade is often misperceived as being worth more than it really is. If you buy something mid-to-top range you are really only going to be able to get a single upgrade cycle out of it out (where there is some substantial marginal benefit for the cost) before the rest of the system starts to obsolete itself. If you watch things closely and the tick-tock cycles are aligned then maybe you get two.
It’s a fun hobby. And if you have the cash to spend on always having the best GPU then you probably don’t care that for $1,000 you only get an extra 10 FPS or so.
These days I can’t even remember how old a machine is let alone what GPU it even has. “Why is this box so slow? It’s four years old? Holy shit, when did that happen?”
Even when I had a rig and was reading Tom’s and Anand daily I don’t think I actually ever upgraded a video card twice. Maybe it happened once? The cycles might have been longer back then, but by the time cards had advanced two generations we were moving from AGP 4x to 8X or to PCI-E or multi core whatever. I could easily just go back in time and buy whatever middle of the road Dell lunchbox was available and just replaced the whole thing every year or two and probably saved money for the same performance.
These days I’ll take a non upgradable whatever it is as long as it has a good warranty.