Let me offer a different point of view.
LTS is useful if you find yourself playing STO semi-regularly. Getting instant access to all the veteran rewards is amazing. Especially helpful are the additional bridge officer slots, ship slots, respec tokens. It means I can upgrade my characters, shps and bridge officers without having to spend zen buying additional slots. The VA ship token and Veteran Starship means I get access to a decent (not best) level 50 ship. Individually, it does not seem like much but it is 3000+ zen PER CHARACTER that you don't have to spend. I have 9 characters, so that's a saving of 27000 zen. This alone is already covers the cost of LTS.
And I believe the monthly stipend is 500 zen? Either way, the zen savings above plus the stipend means I don't have stress about not having enough dilithium or zen to get what I want. I can stop playing for a few months and come back with enough zen for a new ship.