I doubt its age has much to do with it, and if it does then it’s a really really stupid reason. If no one wanted to drive older cars then why would Turn 10 added another old formula car with the Alfa 158 when we have newer formula cars available?
Can only speak for myself obviously, but I’d much rather drive the Speed 8 or TS020 than an R18 or 919.
No, but maybe this car didn’t fit into their new homologization rules and they decided to cut it. Or they noticed nobody was using it and cut it. Today, devs track everything you do. How often do you drive a specific car, how many trunks you open, the badges you select, it’s all tracked. So cars that don’t get a certain number of uses will probably not get a renewed licensing deal if you can spend the same money on a different car that attracts more players.
I would imagine it will boil down to a licensing agreement conflict. Like you stated, it was the ONLY Bentley LMP in the game, and obtaining a contract for a single car that would be (for all intensive purposes) mainly in the game for nostalgia would be time better spent contracting with another manufacturer. I mean, Forza 4 didn’t launch with a single Porsche (or was it 3? I can’t remember), and that was all licensing. Don’t get me wrong, I’m not defending T10 here, in fact I’ve had numerous run ins with moderators and admin about other issues, but we do have to look at the big picture before saying “it’s just for money”. The Speed 8 may come in DLC after an agreement is made in licensing.