Over the years, Rituals have probably gotten the most revolutionary support cards of any monster color, and that's for good reason. The Ritual mechanic is generally pretty difficult to pull off in a regular duel without any help whatsoever, requiring a specific monster, a specific Spell, and enough monsters to Tribute that are either on the field or in your hand.
Recently, I was re-reading the spoiler for Legacy of the Valiant and yet another one of these revolutionary support cards happened to make an appearance.
This card's current translated name is Light Dragon Ritual, and it's highly reminiscent of a former card used by Kaiba. The reason why this card caught my eye is because it's capable of what's essentially a reverse Ritual summon - instead of needing monsters and the Spell itself in your hand, you can do all of this from the Graveyard instead so that you don't have to set your card advantage on fire.
This concept really interests me, but I feel that instead of specific improvements here and there, Rituals need a complete overhaul. And obviously, putting them in the Extra Deck would go a long way towards helping that goal. Most of the other "special" colors of monsters already go there, so why not Rituals too? This way, you could forget about having to draw or search the actual monster card in order to summon it from your hand. Of course, Extra Deck space is a bit of a concern, so it'd be cool if there was also a rule that allowed you to play up to 3 Rituals in the Extra that don't actually count towards the 15-card limit.
These things are likely never going to happen (and man would they confuse people if they did), but it's just something nice to keep in mind. After all, this game will never get better without people thinking outside the box and coming up with ways to actually make it happen. Thanks for reading!