Barriers and support pick ups are useless? Now it's just fine for you to be stating an opinion, but perhaps a bit of clearing up on what they do may shed some light on why they shouldn't be completely removed.

Barriers are actually some of the more useful items. They deal more damage than expected as long as you can give it a break from invinciticks. Not to mention they basically spread a status effect to anything and everything around you provided they get hit once or twice.

Support pickups? Do you mean like the Mechas, Recon Flares, and Air Strikes? Well Mecha Knights (or as I like to call them Mega Noobs) may be awful fighters, die quickly, and try to kill you indirectly, but they do make great meat shields. After all, their only purpose is to protect the knight that powered them up.

Saying that Recon Flares are useless is like saying a Blitz Needle is bad against Vanaduke. Now not many people understand how they work, but once you do they become the most useful and valued items of your selection other than Health Capsules. They make better meat shields than Mechas due to their higher health, they can actually help get a bit of damage done to a few enemies, and most importantly: death mark. The death mark will make all monsters around the Flare get their defenses dramatically decreased. So much so that a shadow weapon against a fiend or undead monster would probably kill it in 3 hits or less.

As for Air Strikes, well. If you get lucky enough they can be truly devastating. But the chances of them missing are pretty high. So I don't have much to say here.

In my opinion, they should stay the same way they are now. Though a few minor changes here and there would probably be for the best.