I mean, the Rasengan isn't really that much flashier than breathing fire or erecting a wall of mud out of ground that wasn't mud.

Or creating dragons out of the elements.

I'm sorry but the dislike of it seems pretty arbitrary to me and every other A-Rank/S-Rank technique is pretty comparable to it. S-Rank Taijutsu lets you warp the fabric of space from the heat of your body and the physical force of your body's movement while completely obliterating most of the body of someone with superhuman durability and ridiculous healing factor.

The main difference is the sheer amount of skill involved: Per Minato's intent, the Rasengan is the ultimate mastery of shape manipulation, generating pure chakra into a solid form and rotating it in every direction at once without the use of hand signs. One could argue that it's the purest form of Ninjutsu and there are no other techniques that require the same level of chakra control.

If you don't want to use it, Senko probably will if only becuase... I mean, of ll of the people confirmed to use Sage Mode three of the had the Rasengan, one of them was the single greatest Medic Nin in history, and one of them is a genetically engineered composite who was designed to be ale to use Sage Mode. If you can use the Rasengan you've got the necessary chakra control to learn Sage Mode.