Sensationalism/puritanical stupidity will always color this as "depressed and lonely" in the same sense that anyone who masturbates is a freak who can't get a real partner (and those crowds are ALWAYS implying a cishet partner...).
"Sex robots" are more or less a middle ground between a masturbatory aide and a prostitute. People who use them aren't looking for (simplifying) a girlfriend anymore than someone who has casual sex is looking for one. They may be looking for a way to blow off some steam. Sex releases a LOT of really nice chemicals into our brains and, if you do it right, is almost meditative when it comes to clearing thoughts.
Some are looking for a way to "get practice" for a "real girlfriend" because media makes them think they need to make their partner orgasm with just a single look. When the reality is... if you even give half a shit about how your partner feels you are well above the vast majority of people out there. And, if you actually ask for feedback and follow it, it is gonna be god damned niagara falls down there. The good Canadian side.
And, with the rise in long term long distance relationships as well as the acknowledgement of asexual folk, it can be a way for one or more partners to get what they need out of a relationship without burdening the person(s) they love.
I dunno. I generally hate most coverage of these topics because it invariably involves folk showing their crusty poorly wiped asses. Sex positivity! But only if you have sex the way the good book says you should (... with your daughter and against her will?). Same with when sex work comes up. It INSTANTLY becomes the assumption that anyone who has ever considered sex work is involved in human trafficking and blah blah blah. And some of that does happen (it is almost like legalization means victims have somewhere to go for help...). But it ignores the idea that someone might just realize they can trade their body for money in the same way that athletes and "the trades" do.