It's more so the loot. Theres... nothing unique about it just tons of it. It's not like ER where you get a really badass 2hs, you just get random tiers to drop like Diablo without the unique items. It really turns me off.
It's definitely annoying, especially early game when none of the stats even really matter at all. It's nice if your weapon is imbued with an element (preferably not fire, since the best early ninja arts--fire shuriken, shrapnel bomb, uncanny flame--can be used to apply burning and ideally you want a second element so that you can confuse bosses for big +dmg), and for armor there's a few affixes that increase the only base stats that matter (hp/def/toughness). Aside from equipment and crucible weapon drop %, all the other affixes are so small a boost that they really don't do anything noticeable.
You can mitigate it by making changes in the settings menu though. First off, turn on auto-pickup so you just walk over the items instead of having to RB them one at a time. Then set everything up to uncommon to be marked as junk whenever you visit a shrine. You can either donate them for amrita, sell them for gold, or disassemble them for crafting mats. Personally I recommend doing about 50/50 donating and disassembling in the demo, at least until you max out the donate titles. After that switch to selling and disassembling, and only donate weapons you've maxed out familiarity with because they give a very large amount of bonus amrita. Later on you unlock a fourth option (soul extraction) that will replace disassembling for the most part. You'll also want to bump the junk filter up a tier to include purple items once you're a bit past the demo too.
Later on, once you start getting item sets that boost the weapons/build you want to play you can make use of soul forging at the blacksmith to improve your drops/crafted stuff and you'll be looking for trash items with specific affixes in order to inherit them onto your good gear, and that's when the loot system finally gets interesting.
Edit: Oh, and while you're messing with the game's settings, do yourself a favor and switch controls to Type B. The default left-stick forward/back + square/triangle input for a whole bunch of arts is pure ass. Type B changes that to LB+square/triangle instead.