Cole I'm not trying to sound combative but Why? Opinion on quality differs from person to person. Justin Bieber is a huge act (he's still a thing right?) that draws in huge numbers, but I would say I have no interest in seeing him. For me they have had some bands I like a lot especially recently: Weezer, 3 Doors Down, All American Rejects, Matchbox 20, 30 Seconds to Mars, etc.
Huge names are just not going to play there because there isn't enough money in it. Universal is only doing it to drum up some business on a generally low attended time frame as a free concert and maybe a thank you to AP holders. They can't handle any crowds bigger than some of these performers are bringing in. We did have a TBD last year that was someone you are praising, Weezer.
They usually do have 1 or 2 Spanish acts.
Typically the parks are pretty quiet until 5 or 6 when the people for the show start coming in, Finnegan's is generally pretty busy though.