Item's daily limitation

[Marcloure]

Very recently (some minutes ago) I discovered that a character can only use 1 daily power from items per tier per milestone. I also discovered that Essentials removed this limitation, and introduced rarity to items so "not all items are sold".
Considering I'm DMing without bothering with rarity until now, is this limitation necessary? I mean, it kind of ends with some cheap tricks like everyone having a Cloak of the Chirurgeon and also makes days with only one or two encounters harder (they can't just burn all item dailies at once). But in terms of power, is the rule needed?
Until then, I have given my players more of lower level items than the recomended. But knowing this limitation, is it better to give them less of higher level items, more higher level items, or just nevermind this rule at all?

[tiornys]

The rule exists to restrict players from buying/crafting numerous copies of a lower level item (taking advantage of the cost scaling--e.g. a level 15 item is the same cost as 5 level 10 items or 25 level 5 items) in order to spam that item's daily power. Rarity addresses this issue in another way by (ideally) gating the better daily powers behind higher rarity. As long as your players aren't being abusive about the system, you don't need to worry about it. If everyone starts to show up with a ton of Power Jewels in mid-Paragon, you might want to talk to your players.

[Kurald Galain]

The game is built on the assumption that low-level items are useless to high-level characters. However, this assumption is clearly false, and the exponential money curve allows high-level characters to get practically unlimited amounts of low-level items. Hence, a variety of kludges were put into place to fix this blatant gap in the rules. These include magic-item-daily-uses, rarity levels, heavy errata, PFS item restrictions, and probably some others.

If you have power players, this is very much necessary. If you have casual players, it's not and they probably won't notice.