1. That is still different gear and while it might not take long its time spent on redoing the same loot for little to no reason.
2. I could care less about making it easier for ppl to pad their item lvl and cheese their way into runs they dont have the gear to run and get carried by others.
3. You are always going to run into this issue as new content keeps coming out. Do you not want them to release new 5 mans or quest lines with each raid or large patch? You do realize your 3rd point is one of the many reasons they didn't make normal 90 5 mans.
When it really comes down to it call a 5 man whatever you want, if its fun or you could use the loot run it if not dont. Ppl get far to caught up on the color of the text the names of their items are written in and where they got it from. When new content comes out and a expansion goes live purple doesn't always mean better and item lvl most certainly doesn't mean better. Trinkets are the best example of this, there are always a few trinkets that are awesome well beyond the tier or raiding you get them in. Sadly many muppets swap out of them because they want to go up 1 average item lvl on their character.