Re: No, it wasn't a welcome
It's extremely difficult to give constructive criticism of artwork at the bets of times and really it takes a bit of time to get to know someone to get some sort of context for what they are doing. It's almost impossible to say anything very useful about a couple of photos of work in isolation.
Similarly it can be a bit of a no win situation offering critique, as the most useful things tend to come across as negative as the nature of art tends to be that it either works as a whole in which case there isn't much to say or there are one or more elements which are problematic and are in themselves minor so good critique often ends up sounding like nitpicking. But that is exactly what it needs to be.
So in reality just asking for criticism out of context is a bit pointless, you need to engage with people and try to get a discussion going by asking the right questions.
Finally writing a worthwhile critique beyond 'that's really nice' takes some though and care so you're asking people to go to some effort to do something that they know the chances are won't be very well received.