Honestly, I'd like to see Alignment minimized in importance. I think at this point in the game's life (meaning, on this server with about 500 individual log-ins a week) Alignment arbitrarily barring characters from content that they would otherwise qualify for is destructive to the server.
While on live there may have been significant differences between the sides pre-Going Rogue, much of the content added with that expansion and after was cross alignment. Cimerora, the Rikti Warzone revamp, Dark Astoria, the Wards, all the Incarnate trials, TinPex, LGTF, etc are all activities where anyone can play together regardless of their alignment. Certainly, many of these tasks are wrapped in some bit of text that explains why the threat is so large that heroes and villains might work together, but I wonder... who really needs weak prose from a decade ago to tell them who their super-person is and why they make the choices that they do?
Certainly, I see value in carefully considering how and why certain decisions were made on live, but I question what value being a Vigilante has on Rebirth right now. I've played at least 15 characters up to 50+, none of them farmed. Many of them have changed alignment for various reasons, but I can't recall ever having one of my Vigilantes join a red-side team that wasn't doing Villain tips. Very little happens red-side, especially if you view our tiny server base in the scale of a global server population spread out over the 168 hours in a week.
However, I do see value in being a Rogue. There have been several times that I've brought Rogues over to do blue-side content. In fact, it's rare that any teaming that my Rogues have done hasn't been in the company of blue-siders because of the aforementioned lack of activity on red-side.
My point here is not to boost one Alignment over the other but rather to suggest that maybe all the Heroes could be treated like Vigilantes and the Villains treated like Rogues to even the playing field and allow our small community to play as broadly as they like. Why not de-couple the zones you play in and the content you can join from the arbitrary alignment system that the developers on live consistently worked AGAINST with the aforementioned open-play content of iTrials, DA, Cim, etc?
I'm not suggesting that Heroes can go get Villain contacts (though I'm not against that), but simply letting all characters, regardless of alignment, play on either side.
If people really need something special to hang their character's identity on in terms of being a Hero/Vigilante/Rogue/Villain that their own imagination can't supply, there are still the unique alignment powers, as well as each alignment having its own roster of tip missions. Others have suggested adding Signature summons for purchase and other perks.
Turning the tables on the premise that switching sides is so powerful on Rebirth, though, it is far easier for a new player to the server to make the argument that playing a Vigilante/Rogue is at a huge disadvantage given the current outsized purchasing power of Alignment Merits (particularly given the pile you can collect from the SSA's... provided you can sit through all the unskippable dialog/cut scenes).
That's certainly how I saw the disappointing economics of the game in April/May 2019 when I first logged onto Rebirth. Now with piles of Astrals, a fair number of Emps, and hoards of Purples stashed I no longer care very much about the Alignment Merits; but, if I came on new, now, I'd likely be so turned off by the emphasis on Alignment Merits that I'd probably just go log onto another CoH server.
Mind you, I'm well aware that there may be technical limitations that I'm wholly unaware of, but it seems like a simple solution to just let Villains and Heroes play one another's content, just like Vigilantes and Rogues already do.