Yeah Adepts make Insanity a near cake walk for experienced players, up to the moment the game starts spamming sync killers in ME3. Infiltrators, if you are good, can faceroll the whole game too. And Biotics really don't get shit on at harder difficulties, but you basically have to hand tool your team to generate detonator combos. The biggest issue with Biotics is that they buttfuck your crowd control about halfway through ME2 and completely during ME3. Basically, don't take anything that isn't about making detonators do more damage. You can kind of do the same thing with Adepts, but its harder to coordinate with the allies. Of course an Adept can just wtfpwn a lot of shit once you get the main shield synergy combos rolling without need of allies.
And yeah, they could nerf pistols to half as good as they were and pistols would still be the best weapon, outside of a couple sniper rifles. The cooldown bonus alone pushes them over the top of most weapons, which synergizes further with Biotics/Adepts who want to spam the buttons constantly. On insanity the mid to bigger baddies are such bullet sponges that most guns simply are pointless compared to a pistol/sniper to the brainpan. The last two behemoths on insanity in ME3, as an example, had more HP than any single Assault rifle with a starting load of ammo could kill (granted ammo drops during the fight), which is retarded design. Limitless detonators with ammo friendly pistols make 90% of the non-pistol weapons completely useless.
