This is inane. It's like saying that having a shitty childhood is actually lucky because it makes you stronger. Maybe in some cases elements of that are true, but it's a vast oversimplification of a very complicated situation; it ignores very real issues by substituting a singular potential positive effect.
In this case the big issue is that for ugly people, life is a lot harder in pretty much every way. Social interaction - an absolutely fundamental aspect of human existence - is ubiquitously affected. I'm not just talking about romantic relationships; I'm talking about friendships, job interviews, complete strangers' reactions - everything. A lot of it is unconscious; people just tend to react more positively to attractive individuals.
The implications of a lifetime of ugliness are boundless and often negative - inhibited self-esteem/confidence, bitterness/jealously/resentment, social isolation (and the potential lack of development of good social skills as a result), romantic rejection, depression, bullying, etc. I'm not saying all ugly people have all these problems, but lots of them deal with this kind of shit. Saying that being ugly is actually a blessing is just complete bullshit.
A very pretty friend of mine once tried to tell me that it's harder to be good-looking because others objectify you. I asked if she'd say that to our ugly friend _____ . She frowned. Then I asked if she'd permanently switch appearances with ______ if given the chance. She said, "Well no..."
Meanwhile an ugly friend of mine has been trying hard to meet someone for years but gets rejected every time. I mean he has to try in ways I never did. I am in a great relationship, but it was easy for me to meet someone. It's not fair - he's a clever and hilarious individual - he just happens to be really ugly. He has never had a real girlfriend and it's all he wants. He puts so much focus on it, and it affects him every day. He has confessed thoughts of suicide to me because he's so tired of being rejected. He's worried that all his suffering will never avail him. Breaks my heart 'cause he's a great guy and I wish I could tell him that it'll work out.
To suggest that being ugly is actually a blessing is a thoughtless trivialization of the real fucking shit that unattractive people have to deal with - often through no fault of their own. Fuck that. I've told my friend that I admire him for putting himself out there and persevering but I think he doesn't really give a shit about that. He'd rather not be alone anymore.