Consider for a moment the static nature of the Trek universe up until JJTrek. There were larger scale events, like the Xindi attack in ENT, or the Dominion War in DS9, but no matter how or what happened, the universe always returned to a sort of status quo.
But JJTrek changed that. Suddenly, a major power in the area was hit, and hard. The status quo is changed, knocked for a loop, and as a result, numerous new storytelling possibilities have opened up. Imagine if Tasha Yar hadn't died in early TNG; we'd've lost Sela, as well as many interested character moments for not only Data, but several other characters over the course of the series. Not to mention how screwed Yesterday's Enterprise would have been.
Just... bringing back Romulus, for the sole purpose of having a staging ground for a Romulan faction, stomps all over several potential plot points in favor of the same tired ones from the pre-JJ static Prime universe, with a few spins in the form of New Romulus and Iconian involvement. It's not all that different from the infamous "Death of Superman"; what started as a powerful action, the death of an incredibly iconic character, turned into a farce when they just resurrected him four issues later. That event it credited as killing death in comics. Frankly, I find that idea unappealing.
I'd rather see something like this: Sela, after being taken, has been leading a shadow operation backed by the Iconians, making connections among the scattered Romulans still loyal to her, under everyone's noses. With Iconian tech making her essentially untraceable and giving her unlimited access to anyplace she could want to go, this would be entirely within reason. Then one day, a rift opens, and her clandestinely collected forces spill out, backed by a starbase of Iconian build with Romulan influence - a hub for a faction. Sela, her gathered loyalists, some of her Hirogen allies, and perhaps other species she's contacted in the meantime, form the heart of the faction. Though still far from the previous strength of the RSE, she still commands far more forces than anyone expected.