It's required for the longevity of the game. They have to keep updating this game to maintain a playerbase. It's a fact. If they were to release an update there would need to be a reward worth doing the content for, otherwise it would be dead content on release. The reality is fun can't justify content on its own, so they must add new items with better stats worth striving for.

If the items keep getting better and better, they constantly have to one up the previous BIS. This is power creep, and what happened to RS3. Jagex is attempting to combat power creep by giving themselves more room for useful items, that don't drastically start creeping in strength.

It's a necessary change and although it sucks that they didn't do it earlier, it's still a good thing. They didn't need to do it in the past, because the OSRS team was small and the game was barely getting updating. Now there is a big team and they have tons of planned updates. They need rewards and they've used up many of the niche and BIS items already on things like Raids, Cerberus, and Abyssal Sire.

Adding higher requirements to the items would defeat their introduction as lower level content. Replacing lower level content would require corresponding lower level rewards that would just be dead on release. And they would still lose players from not having new content, even if the current content is balanced.

The OSRS team knows what they're doing.