I keep forgetting GP exists lol. In that case that just adds to why Sony would want TR. More games for their service.
If Sony were pursuing a GP equivalent, then sure I'd see the argument.
Even if Sony were to take the TR IP, there are 2 core issues :
1) Who would develop it? Internally, which Sony studio would want to work on TR? They are being given the freedom to pursue their own ideas which I think we can all agree is for the best. The only alternative would be a 2nd/ 3rd party, but Sony almost never gets an outside studio to work on an existing IP they own. It's always about investing in new ideas and new IP.
2) If Sony were to make TR work, it would have to be an AAA title, otherwise what is the point when they have Uncharted (with speculation that another is on the way). Anything less would be a waste of the IP. The problem, however, as evident by the last 3 releases, is that big budget TR is clearly not entirely feasible. All latest trilogy was at least $100M a piece, profits were not strong, and SE weren't happy with it's overall performance. Sony aren't going to commit to an IP that has been like this for 3 games in a row. Sony barely even gives their own IPs such a chance.