Earlier quoted context omitted.
Sorry to say, your online presence is dreadfully low for a web developer.
Whether this is true or not, there's much better ways to phrase this. > Your online presence is dreadfully low for a web developer. Just dropping "Sorry to say" makes it sound less condescending. > Your online presence is really low for a web developer. Dreadfully -> really. Could argue that this changes the meaning somewhat, but I think the change is more in tone (again, less pretentious/condescending sounding) than…
The claim that your last sentence is more constructive seems a bit weak. what is constructive about it, you basically just derived a logical consequence that touching the website yields a result? Also, what does 'expanding' even mean in this context? At no point did you give any constructive feedback (what should be improved, why is it low, why is it 'really low' etc).
on the note of 'really'. i find 'dreadfully' much more useful than 'really'. much stronger, gives a clearer indication of how bad it really is. 'really' doesn't do anything in this context, let alone be less pretentious.