Yet, people keep playing them.
I had a blast playing FM5, specially with that controller. However GT6 doesn't feel like GT5, is better design, more varied and more fun.
A few bullet points I would like to address here is that, while GT6 looks pretty much like GT5, it feels, plays and the whole experience is way different that it might look, and key thing here is how much time you expend on each game.
I take that FM5 is next gen, but is really all the same, more expensive to say the least. Only mayor breakthrough I experience was the AI, physics were good but they weren't that much of a change from FM4, graphics are supposed to be good given that they work only on a handful of models that were given autovista treatment, which paves the way to a complete set of DLC packs.
Now, while the content is good, the only mayor thing I sensed was how the controller felt, and how the AI was, but this was archived using player data to simulate human opponents, which gives the game a huge re playability level. That said, I only got to play like 3 to 4 hours, time in which I had all sorts of problems with X1 hardware and online features, is kind of counter-productive to have gold membership to enjoy the whole experience, and while it isn't too expensive it is still and added price to an already inflated price, all of this to get better AI.
Meanwhile GT6 has a much better impression this time around, the game plays and feels with driving and progress in mind. Is not a throwing random cars anymore, and while it still uses assets from PS2 games, it is justifiable as long as I get more cars to drive, which is the whole point of a driving game. Events are far more varied than FM5, the experience is far more varied than FM5 (people might argue that Night-Wet driving adds nothing to the experience, but it adds a lot, specially when you consider that visually is a different experience to tackle corners in the dark and manage grip levels on the wet). Yes, GT6 still has circa 700 cars that are PS2 era, but they play like a 2013 game. And even if you go with the whole business of comparing graphics between a old gen and a new gen game, GT6 does manage to match FM5 levels of quality with it's latest assets (Goodwood in an Alpine premium car almost look like a next gen game, and is pretty damn close to FM5 if it wasn't for downgraded AA and a bit lower poly count assets).
FM5 games always felt like completing a check list, this was tamed with FM4 and FM5 threw more variety to the game, personally though I do get quite worn by it after a 2-3 hour session, I was pretty impressed by it, but I have expend far more time in GT6, and I''ve had a better time with, aside from graphics and AI is a terrific game to drive, and while FM5 comes really close it just ... lacks, for me at least.
They are 2 complete different games, on 2 different systems with 2 different design philosophies in mind, which bogs down to what you want from a game, hence why this kind of comparison threads serve no point but to fed trolls and showcase how much of fanboy people can get (and yes, it apply to both sides, not just GT fans).