As a fan of the series since halo ce, I think the way halo has changed is for the better, yes it's a lot different from halo 3 and has a few more tweaks than reach but it makes the game different, if it didnt we would just have a sci fi cod series.
As for story line I only really know from what I play as I don't really read books as I have trouble concentrating, I think every ones main issue is that it doesn't feel like a halo game, I can relate to this as I didn't get that initial feel from 4, but that's because it isn't like all the other games, previously we had to try and save humanity through a bunch of desperate acts that held the fate of humanity in our hands. Halo 4's story isn't like that we survived the war the covenant disbanded and we allied with the elites, we no longer were at risk of being wiped out, that's why halo 4 is so different, that's why the feel the music and general story has changed, we are rebuilding.
Like others have stated jul mdama isn't interested in the prophets great journey, they're interested in killing a hated foe and forerunner tech is probably the best way to do that.
It's not hard to see that surely between 6 or so alien species that some would be more than a little annoyed theat, hay nah it's all good if we stop fighting I mean we have only been at war for nearly 28 years or what ever but I the elites say lets not fight lets not.