Yeah, you could use the Singularity / Warp BE in some circumstances, but it didn't work all the time.
And I say enemies were "as good as dead anyway" after they lost their protections because I always used Incendiary Ammo (either on my character or a Squad power from a teammate), and once enemies were down to health, you could get them dancing in one place and headshot them to death easily.
Don't get me wrong - I liked Adepts in ME2, but the added ability to do biotic explosions on protected enemies made ME3 Adepts a lot better.
Singularity -> Warp was useful every time there were mooks around (i.e. 95% of the time) and it'd do heavy damage in a large area. Pull and Throw were great against solitary mooks - a quick burst or two from a weapon would strip the defenses, and they'd be dead. Warp was effective against heavy armor.
You only needed (well, "need" is a strong word) someone with Overload with you on missions that had shielded enemies - Area Overload -> Singularity would immediately take out a group of mooks - but other than that, adepts could easily handle everything.
I remember well all the crying on BSN at the time about how useless adepts are on Insanity. Most of the crying was baseless. Playing adept simply required a bit more tactical thinking and planning than other classes.
In ME3 adepts are certainly easier to play, but I'm not sure they're any more powerful in relation to other classes than they were in ME2.