Why it takes so long? Well it takes at least 2 years to professional developers to make games, real good games take 5. That's 20+ (nowadays 100+) people working 8 h a day. This is a mod, they are not paid, they can't devote 8 h a day to making it (for the sake of sanity) and I doubt they were 20 people, more like 10.
I've been involved in mod development. It's fun, until it becomes too serious (is there anythng more serious than making a remake of HL1??), internal "deadlines" are set, and there's high expectations (quality expected everywhere), etc. Then it becomes a nightmare. It's your free time and instead of playing or being with family members, you have to spend a significant amount of time, doing the exact same thing you do on work, with deadlines and expectations that resemble way too much your actual work, despite suposedly being a hobby. No one really sets these expectations and deadlines, other than you yourself and your partners, but at this point you do feel like you HAVE to go through all of that, because there's people waiting for the mod and you want to succeed and finish it. In comparison to BMS, it was a very small mods I was involved in for HL1 and UT, and the audience was very very small, I can only imagine the nightmare that the BMS team has gone through.
So no, I don't think it's reasonable to criticize their work in that manner. I'm mostly talking about midget here tho (no offense). I think it's reasonable to ask when it's going to be released, etc. But to complain about the quality or the gameplay and whatnot... I think it's essential to first ask yourself if you would go through all of that, and how much of your life would you be willing to devote to it, before even commenting on the issue. It's taken them 8 years, yeah, "wtf I had to wait 8 years", right? No. Read the above paragraph again and think of it from their perspective, yeah, it's been 8 fucking years!!! Be grateful or stfu ffs... (again no offense to anyone)