The more I think about it, the less need I see for skill requirements in quests. It's really just a reflection of the way the game has evolved since they were relevant: every novice quest released over the last few years has forgone them, while the grandmaster quests released alongside them have not used the skills they required. Put simply, we've reached the point where they're utterly meaningless.
I know I was on the losing side of the poll for this one, but what we need is a new measurement system. Luckily, the groundwork for it is already in place, and has been for years now. Most newer quests already use it as well so, for many players, there won't be much of a change.
Remember Rag and Bone Man? That kind of system might work better with the current state of the game. Minimal requirements for the base quest, with a steady increase for optional tasks after the fact, all of which are required to qualify for the cape. Sound familiar? Oversimplified as it is, the system used in the past for the quest cape is already in use for the (trimmed) completionist cape, though instead of bones, we have to collect background details and bonus lore or do additional tasks for additional rewards.
Keeping 'hard' skill requirements to this bonus content would also be in line with their insistence on having major plot developments be available to the entire community: potentally expanding their options in regards to high-level characters such as Zaros: characters who (I assume) are being kept out of world events and similar grand-scale content because of accessibility. As it is, important, world-changing characters can't have a permanent impact on the world because many players won't have unlocked them.
This way, everyone would have access to the lore, and more tangible rewards would be earned after the quest, with appropriate levels. More than that, it would allow them to neatly sidestep the logic issues that making another The World Wakes would cause: where you have to train to be able to do something your character has already done, or having to train when you've 'done' a quest with harder requirements.
Why, though? Because this is already the direction that the game is heading in. Recent bosses have scaled to the players' levels and almost every quest since the Desert remakes has had bonus high-level content at the end of it. All this would do is to make it an official measurement, rather than something that happens alongside an already broken measuring system.
Though perhaps the real reason is that the last big quest which used every single one of its requirements was While Guthix Sleeps, while some of the more recent quests have had little to no justification for their classifications (such as The Mighty Fall being a master quest with higher requirements and more intensive combat than some grandmasters), which does nothing but rob each category of what little meaning it has. If quests really must be level-locked, total level would make for a better means of measurement than whichever skills they happened to pull out of a hat.
Ultimately, the current rating system is an artifact. It should be tweaked or replaced simply because it isn't doing its job anymore. Regardless of what sentimental players may think, there are better systems for measuring difficulty than one that hasn't accurately done its job in nearly half a decade.
