To get straight to the point, ESO is an MMO. MMOs are meant for players to play together not solo (hence the mass MULTIPLAYER online). I think the difficulty of vMSA isnt the problem, its the pure frustration comes from the overall simply put non-enjoyable content. Sure the first completion might be fun for some bc of the challenge, but there are so many things that could be solved if the arena was duo content. such as:
1.Tanks & healers wouldnt have to reroll or become a dps to beat the content.
2. Being MMO players it just makes sense that playing with someone would be more fun/less frustrating than playing alone.
Now obviously the mechanics would have to be adjusted to maintain the difficulty of the arena (which i think should remain a constant), but with the right changes vMSA could go from being frustrating, repetitive, and tedious to fun, enjoyable, and rewarding.