I agree lack of kisses or overt sexual tension does rob the pairing somewhat; but I'll disagree it made them 'less' yuri. In the series, SuleMio has chosen each-other over and over again, refusing or rejecting other options that's easier/more advantageous to them in favor of being with each-other.
Well, except when Miorine entered her Lesbian Self-Sacrifice via Separation arc. it's short, fortunately.
This is also because for interpersonal conflict, WfM favor, well, actually talking. And in most case, both parties are 1) willing to talk, and 2) it's actually effective.
The one where it doesn't, of course, lead to giant robots fight.
So, combined this signals all those choices given? Yeah, most of the time they both get pretty clear pros/cons of it. And they choose each-other. And that's why I don't mind much there's no kissing and clam-slamming.