As others have mentioned, the tripod ring is not essential with this lens. It's not a matter of weight or size.... it's just a very useful convenience. I've always had a collar on my 100mm.... But I do a lot of macro shots with a tripod or a monopod, so the ease of changing from landscape orientation to portrait orientation is very helpful to me.
The Canon tripod ring is pretty expensive. There are far cheaper "clones" on eBay and elsewhere, that seem to work every bit as well. Just look up the model number of the Canon item and use that to search. You'll find alternatives that can save you a lot of money.
Another "trick" that the t'pod ring makes possible... often macro is most easily focused manually. A common technique is to move the camera and lens closer to or further from the subject to achieve focus. There are geared "focus stages" that mount between the lens and tripod that make this easy, but they are pretty expensive and heavy to haul around. If using an Arca-Swiss type quick release platform on the tripod head, you can simply fit an extra long A-S lens plate on the tripod mounting ring foot, then slide it forward and back along that... It's sort of a "poor man's" focusing stage. Works well, plus saves money and weight.