That's personal preference. For me, the charm of DCS is hitting the buttons and switches. It's what makes the game feel like a simulator. I use track IR to look around and find the button I need in my cockpit. I want a co-pilot for this.
Navigation, spotting targets, calling missile launches, as well as having someone to take the controls while I go get a drink are some of the advantages multicrew brings. I find flying tiring. There's so much to do. I want to do it with friends. The only way I can see this being terrible is lag. If my Mi-8 is warping all over the place, I'm not gonna want to fly.
In multiplayer servers, I'd love to see multicrew counted as one player from a balance perspective. Otherwise it makes more sense to just bring more airframes.