Haha. Peace, in response to the "going commercial" complaint, definitely... that particular album was in the late 70s and had a more polished "pop" sound, with definite influences from the disco age... That era was bemoaned buy some as "Disco Dead."
I would warn you not to get me started talking about the Dead, because it is often hard to get me to stop talking about them once started... I would agree that their vocals aren't particularly polished and the instrumentation much the same....
But really, they're a folk band playing Americana in a jazz-influenced (improvisational) style. Two relatively infamous quotes sum up their appeal to me...
First, "they're not just the best at what they do, they're the only ones at what they do." They were famously and proudly unprofessional. They hated practicing so they'd just show up at a show and more or less wing it. Hell, where most rock bands try to keep things moving from one song to the next, there were times these guys would just stand around on stage for a while between songs, tuning and chatting before deciding what to play next...
Second, "there's nothing like a Grateful Dead concert." Listening to the music or watching a video only gives you a hint at the experience. The sounds yes, but the sights, the smells, and, yeah, let's face it, the drugs... Haha. Sensory overload.