Falling behind on magic items

I think I have been too stingy. I was thinking about what I would do about characters carrying off items. It seems unfair to allow precious items to be carried off without replacements for newer characters, but I don't want new characters to come in with hand picked items as opposed to random items.

Looking at the distribution of magic items in my current game I have fallen behind. They have missed 3 items. I feel to make the party up to snuff I not only need to replace these items and to also to 'reopen' the slots being taken away by other characters.

Another thought I had was that I should make these random items better since they aren't as useful as items attuned for the characters. This is the effect I want, because I want them to have to adapt to items they find and not develop item based 'builds'. But this also makes them a little weaker than normal. I think I will start boosting the level by 2 and having any consumable rolled by a pure addition. I don't think +2 levels will be unbalancing since an additional +1 usually takes around 5 item levels.