It is a little odd that with the Rally events being point ot point that you can't create point-to-point races yourself... But that might be just one more thing they pulled back on at the last minute... like;
Damage with AI cars... (probably to easy for the AI to crash themselves out or take advantage of and no AI programing for proper DNF and getting the car off the track)
Limited events... (It's clear there can be more events but instead of numbers of events they might have had more detailed ones with required pit stops and rules... again AI probably couldn't handle them convincingly)
Linked events like the "Italian tour one" in special events... I really liked this with the movies going from car to car/event but it looks like others like Nascar and Rally got their parts cut out... We've seen them in trailers but they are not in game
Proper Rally events... (again, probably an AI issue as it uses a classic "way point" system with little contingency algorithmic pattern to handle unique situations so they do the "Loab" tactic/style of going as straight a line as possible... We the player can get all sideways and aggressive, utilizing things like the E-break, and destroy the AI... so they kept it to token events)
Reward cars... I bet there was a much more robust reward system when and if there were a lot more events but in loosing events it looks like it made the reward list look a bit silly... It's absolutely pointless to get a Fiat 500 after you have been spending most of your time with updated production and race cars with little reason, specific event or otherwise to go drive that car other than novelty value.
Only 200 premium cars... (I believe GT5 was never meant to have these and they were reserved for GT 6 as there are so few... 6 months to make a car isn't what many think... it's not a linear process, it requires art, LOD, physics values and attributes, etc. all can be done at once or in a staggered fashion, you don't need a complete car model, just the values to apply physics... so it's more like 6 man months and PR thought it was a great line, as they did this in every GT game... GT3 was what, 3 months per car? How many cars were in GT1? How many cars in GT2? Then GT3? and then GT4? - rhetorical question)
Missing tracks... (and honesty we are lucky to have some of the ones we do, look closely at Edger, the ribbons going around the track say "2006"...)
Missing tracks from events... (look how many tracks aren't used for A-spec... my guess is again, AI... they just didn't get them set up quite right to be convincing using their OLD way point system...)
Horns...? never mind...
GT5 appears to be violently butchered more than scoped back... to me I think AI (as one of many I'm sure) was a wall they couldn't scale as they have done remarkable things with the technology, physics, car models, track recreation, intelligent decisions to reduce track detail in favor of making sure the whole replay and on track package flows nicely and is consistent, a fantastic high contrast lighting model, etc.
So we have a pretty amazing tech demo! PERFECT game by standards of yesterday, but not what any GT enthusiast expected when using a very honest assumption of evolution over time.
Sorry to belabor this point but its the list above that has me waiting to see how they get what was ripped out back in... Sometimes scoping down a product can be just as hard as adding new features late... Developers can easily put themselves in a corner, held hostage by their own efforts if not managed well. And let me tell you, 5-6 years in deep development isn't much different than being in prison for 5 years... You get used to things and loose sight of the real world... and once its time to get back to the real world its a very hard adjustment...
OK, this is my LAST long post... here...