Literally the only advantage to the G29 is reliability. It's essentially a G27 with a few more buttons, sold at twice the price, and without a gear shift. The TM300 wheel outclasses it in every way for about the same price.
As
@BrandonW77 mentioned, yes they do. I had the same optical encoder issue and had to exchange my wheel after 6 months, and had a problem with my DFGT brake pedal that required some engineering to get it to work properly again after 2 years.
No proof has ever been provided for TM exclusivity. See the last few pages of the thread, it's pure speculation.
No they didn't. I can still walk into Best Buy in my home town and by a brand new G27. The G27 has remained in production even after Logitech announced they were leaving the console peripheral market. They never left the pc market.
Since the G27 is still in production, creating drivers to make it work on the PS4 makes sense because it would be the go to option for anyone looking for a really good mid-range wheel and it would be postioned as by far, the best wheel value on console. They'd sell by the boatload. They could still have released the G29 as their only fully compatible wheel, with the extra buttons and knobs etc and it would still sell.