Having done both corporate and 121 flying I would say that the flying is definately different, as are schedules, lifestyles, and situations encountered. It's not to say that one is more difficult than the other. They are equally challenging and equally rewarding, both in their own ways.
There are some 121 jobs which are easier and you get treated better by management. There are some corporate jobs which are easier and you get treated better by management. There are some airlines that require high time because they can, some because they have to. There are some corporations that require high time because they can, some because insurance mandates this. Right now corporations seem to be more desirable because people feel they are treated better. That's not always the case.
I think the original poster was describing exactly what is happening here. As opposed to cutting each other down because we fly different types of iron to different places and different times with more or less people aboard, why don't we support each other. We are all pilots, some have chosen a particular road because it was easier, some because they wanted to.
Additionally, regarding the those "300 hour" pilots, technically aren't they pilots too? Did they not get the same job you did (some of you), but with 300 hours? What does that say about your skill, your professionalism, your personality? I know, an overly simplified and very crude comparison (not examining external factors of course) but it got you to think about it anyway

. However, at one point in time, every pilot that has ever had 300 hours and wanted to be an airline pilot might have very well given a body part to get that airline job with 300 hours. I have flown with many pilots, some with more hours some with less, but I've learned something valuable from them all.
If some feel that safety was at issue, I then ask howcome nothing was done about it? As pilots, we have extreme confidence in ourselves, however, the only confidence that matters is that expressed by our passengers towards us. And that includes far too many aspects to list. But an important cue for most is how we treat those around us both personally and professionally. If you have problems with a person, be a friend, be a coach, be an ally...in the end the results are far more positive than simply being a critic.
I am by no means singling out people or groups, offense is not the intent, and this is not the proverbial "why can't we all just get along," but like the original poster said, we're professionals, and I guess that's what I took it to mean. And yes, I once had 300 hours too, but that was a long time ago.