The reason why grappled is so good is that getting out is a contested attribute check, and requires an action, and bypasses legendary resistance and it has synergy with prone, which also has these features via shove action.
You can nerf enemy attribute checks and boost your own far easier than you can do the same to saves. And burning an action on a BBEG is rather strong.
Hex, Enhance Ability, Expertise, max Str means you are walking around with +13 (level 8) to +17 (level 20) athletics and advantage, while they have disadvantage. If you can arrange to get Huge an ancient red dragon only has a +10 athletics (30 str).
2d20+7 pick highest being beaten by 2d20 pick lowest is rather unlikely. So you then knock prone, and everyone has advantage on the foe, and the foe has disadvantage on all attacks, and cannot get up with 0 speed.
But none of this is due to the condition itself. It is because the condition was weak enough that applying it was made so easy.
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To that extent, you need to talk about not just the condition, but the duration and how to get out. Paralyzed where you break it on damage, is weaker than paralyzed where you get a save every time you are damaged is weaker than paralyzed save each turn, which is weaker than paralyzed for a duration.
Conditions are not just free form units, but need to make story sense. Petrified doesn't "go away" like stunned usually does. On the other hand, becoming petrified usually is a multi-stage process in 5e, giving people a chance to break free or help.
Charmed, while minor, often comes with riders "while charmed".
Removing that texture -- the connection 5e does with effects to the underlying fiction -- breaks an important part of what makes 5e 5e.