I'm with the OP on this one. The Romulan Republic is a faction. Although I admit that it's not quite as some have expected it, the RR will be its own faction.
I don't get why people get the term "alliance" mixed up with "subjugation". The KDF and Fed. helped these Romulans stand on their feet again, building New Romulus with them, so it's natural at this point that they'll be allied with them.
And don't tell me that PvP mumbo-jumbo that Romulans will kill Romulans for the Feds and KDF. If we look at it like that, then Feds. kill Feds. in PvP for the sake of fun, can't see the Federation breaking apart over it.
This is merely a choice a Romulan commander will make in terms of who does he/she want at his side when engaging the Tal'Shiar, Borg, Tholians, etc., a Klingon warrior or a Starfleet officer.
A Romulan commander will wear Romulan uniforms, have Romulan insignia, will fly a Warbird with R.R.W. prefix, enjoy Romulan Ale in the faction-specific hub, answer to his/hers Romulan superiors and immerse in unique content. So, yeah, it is in fact a faction. Go figure? How does being allied with someone instantly make you their lapdog I will never understand.
This was completely how I felt up until I gave it some more serious thought. The only thing which changes this is FLEET SHIPS. If you think about it - the chances are no Romulans will actually end up flying Romulan ships because they will have outgrown T1-4 and the C-store T5 ships won't be as good as fleet ships.
You'll get Romulans flying about in B'Rels and Fleet Defiants. THIS upsets me. I would be completely 100% behind you if they added Romulan Fleet ships exclusive for Romulan Characters (allied to both FED and KDF) and didn't allow them to fly FED/KDF ships - but that's never going to happen.
Starbases/DOffs I can get behind. Yes it's a little weird to have 5 Romulan Bridge Officers and a crew of 200 orions, klingons and gorn - but that's a small sacrifice I'd be happy to make.
But please Cryptic, don't make them able to fly standard c-store and fleet ships from their allied factions, it's a terrible idea