Hello folks! Very interesting topic here and have encountered these attitudes throughout my playing career. I'm a new member here but not new to drumming. I am celebrating my 56th year as a drummer and I have found this issue of playing cover songs "note for note" or not to be somewhat of a generational thing. I grew up through the 60's, 70's and 80's playing in cover bands almost exclusively. Back then, there was this "unwritten" understanding that you worked your ass off to play the music as it was written. For instance, with regards to guitarists, if you couldn't replicate Eddie Van Halen's tone and play his riffs exactly, you wouldn't dream of trying to play Eruption/You Really Got Me in front of a live audience.
As a drummer, I wouldn't have dared to play the entire first side of Rush's 2112, Red Barchetta, Limelight and The Trees (which I did in a band back in 1982) without woodshedding for months (which I did) to get Neil's grooves and fills "under my hands", so to speak. When your covering music, you have the original recording for everyone to compare you by. As such, when a band plays a song and key elements are not played, or the tone of the guitars isn't just right, or the groove "somehow feels different", it leaves the listener thinking "wow, that just doesn't sound right" or "well, they tried but missed". I've told many of my fellow cover musicians over the years that ". . . the only difference between you and a juke box is the lack of a coin slot behind your ear"! LOL (always helped to keep the egos in check!)
Fast forward to 2012, I played with a bunch of guys that grew up through the alternative rock/grunge era. Again, a cover band, we covered everything from Pearl Jam to STP to Silverchair to The Foo Fighters. These guys really didn't care that key guitar parts weren't being played or that we didn't get the vocal harmonies right. They just wanted to have fun and jam out in clubs, in front of people. It's not that the band sucked. They didn't. We were actually pretty decent and the clubs loved us. However, by our 1980's standard of perfection in playing and performance, it was much looser and not anywhere nearly as "tight" as we were back in the day. Much like the rock music of the 80's was much "tighter" than the alternative/grudge which sounded more like garage bands by comparison. No offense to any alt/grunge lovers here as I too like much of it. It's just stylistically different. It's meant to sound more raw, less "produced" and actually invites a little more sloppiness. To that end, these guys didn't see the "merit" in trying to get it perfect. As for me, I've still try to stick close and pay "homage" to the original groooves and fills (particularly if it's a truly "signature" part). Does that mean I never take poetic license from time to time? Of course not. If I do decide to introduce something new to the mix, I make pretty damn sure it's an improvement to the music before I do. As an example, I've played the song "Children of the Grave" by Black Sabbath in many, many bands since the mid 70's. Somewhere about 1985, I altered the intro of the song to include a 16th note triplet pattern on double bass along with the floor tom pattern that Bill Ward created. During the verse portion, I chugged out triplets to match the guitar/bass pattern and in the chorus I would go back to 16th note triplet pattern to really drive it home. Those were big changes to a classic song but, in the end, it really gave a fresh, slightly more modern punch to an already great song and I've played it that way ever since!
Sorry for the long post, I'll try to keep them more brief in the future but, like I said, it's a topic I've encountered for a long time as a player. Happy to be here with you all and looking forward to reading more!