I've been criticized here for removing grain from my encodes...

As poita said, you take a big compression hit by leaving in the grain so it's a bit of a tradeoff whether you want a more filmic appearance, vs. better compression, and I tend to prefer a sweet spot that still has a little bit of grain, it's not swimming in it like say the Dragon Ball Z Levels, or the Puggo 16mm encodes, but it's not completely grainless, flat and looking like video.

Of course for the master preservation from which everything else derives, you want everything intact :P - you can take something away, but you can't add it back later.

Just an opinion on my end.