Caporegime
Moyes was a (big) mistake, but I still feel it was the right thing to do at the time. IE United HAD to TRY to bring through another homegrown manager. As you said, Fergie hid a lot of deficiencies in the squad he left, he was just biding his time until he walked away (from being manager).
His bigest crime imo was leaving the squad in such a mess. We had a highly experienced 1st XI that really were well past their best in most cases.
I didn't think Moyes was the right thing at all when he took over. He didn't play good football. Never looked comfortable and had nothing to suggest he could succeed at the top level. The fact we gave him such a long contract is a sign that we assumed that it would be a simple transition as well which was madness.
Fergie did leave the squad in a mess as well. It wasn't a horrendous squad, it was just very old, had won enough to not be hungry anymore and Moyes was not likely to be able to motivate them. He also seemed scared or unable to splash the cash on the right players and his fear manifested itself in giving a waning Rooney the contract of a lifetime when he should have been sold.
I don't know about other United fans but I had been frustrated by Fergie for years before he left because he didn't seem to care so much about the type of football we played or that fact that other teams were improving at a much faster rate than us. I can only assume that the glazers were not sanctioning huge spending at the time as they prepared for his departure and the inevitable turmoil it might create. He squeezed every last drop out of his squads but he could have done so much more in Europe if he spent more money.