I married Sumia to my +HP, -Str male Avatar and didn't regret it at all. Grind Sumia for Galeforce? No need when your two daughters joins as Pegasus Knights at level 10, so you can just automatically Master Seal them to Dark Flier! Sure, there's some grinding involve for them, but that's how you strengthen them! Access to all female classes? Look at all the things Cynthia can be! Fem!Morgan kinda resembles Sumia, too! Also, I'm slowly getting her convos with Sully, and already I love the dynamics between the two.
Not to mention that Chrom's royal assets is not a prize for a woman to feel awesome, powerful and valuable. It's just cheapening a character into needing someone like Chrom to define their worth and ignoring anything else. If you only judge a character by its main shtick and not its other attributes- she's a bookworm, for one, which really reminds me of myself, and she really, REALLY loves pegasi, and she even goes off and has a stable of them post game!
So yeah. I'm kinda bummered she didn't had as many suitors as she could, because I LOVE Sumia... especially more after having Robin!Lucas marry her.