The problem is, some suggestions or means of suggesting them are too personal.
PSed retouches of the figure for something like the hair gets into the personal tastes of the person doing the manipulation and people won't all agree on the end look.
Sending real photos of Arnie depicting the look you're interested in for HT to make the call from, that's more concrete because it's what really was, the only opinion is on the chosen style but the actual look was really there.
Even still, something like how his hair should be cut is subjective. We discussed yesterday that his hair changed looks many times over the course of T2. A lot of people remember the poster image style because that's been on VHS tapes, posters, DVD art, everywhere, but there are other looks from the film and HT's sculpt does replicate some of those fine as is.
Things that come down to personal preference really shouldn't be open game for pushing HT to do it, because others might be happy with it as is and your choices could ruin it for them. The fairest thing is to let the company dictate the look and either you like it and buy it or you don't.
Things like he doesn't have a black t-shirt like he clearly wore for the first part of the film, that's concrete, it's no opinion, it's fact and I support calling out for things like that. When details are missed that are factual and not personally influenced, I support the mentioning of it because it does mean a better item for everyone.
Now, some people might being doing PS images just for fun, and that's all cool, I've done it myself, but I get worried when people start talking about blasting this stuff off to HT or whoever because I often disagree with the choices.
Well, These mod, as you say, are personal. I know perfectly well that hot toys will do what they want 
