Agreed, though for a different reason. I don't think the tag match was built up enough to be on the main show anyway. Just doesn't feel right for non-feud matches (with the exception of the battle royal - which still had some build) to happen at a WrestleMania. Would have been cool for the Usos to be in something meaningful leading into the show.
In a 4 hour show they could have easily worked the Uso match in without moving anything....
Andre Battle royal - 25 mins
Title match - 35 mins
Bryan / HHH - 25 mins
Divas battle royal - not exactly a way to get the crowd fired up for the start of the show - 15 mins
undertaker - 35 mins
Shield vs. Authority flunkies - 20 mins
HOF announcement - NO -15 mins
Cena / Wyatt - 25 mins
In my randomly timed matches, there's still 45 minutes to spare for backstage skits, a performance or two and Taker's entrance

.