Before I start, let me just say that I am not saying that transmogrification should be removed. Let me just make that clear. I think transmogrification is a cool addition to the game that certainly made many people happy by being able to wear their favorite gear long after its gone obsolete. I know there's a lot of people out there who are really into it, and some get really creative and make some pretty cool sets.
That said, one of the things that it took away, at least for me, was the ability to look at another player and know exactly what they're wearing. If I saw someone wearing T6, I knew they were a pretty serious raider. Someone with a full PvP set and an elite weapon wasn't able to change their appearance, so you would see that weapon and know right away that they were going to be hard to beat. A lot of weapons were iconic in PvP, such as Stunherald; its appearance was unmistakeable, and in the hands of a mace-specced Warrior, it meant you were probably going to be stunlocked for awhile.
Why does this matter? I'm going to be honest: e-peen. When I first started playing, I would see players around Org with full tier or PvP sets and I would envy them so much, longing for the day that I would obtain the awesome gear they had. And if ever I was on top of the food chain and had a weapon or some armor that was BiS and not many others had, I would wear it with pride. Occasionally I'd even have someone whisper me, telling me that they really wanted the axe or the helm that I had. And, like I touched upon earlier, being able to see exactly what someone was wearing was a way for you to "size them up" and determine whether or not they were a good player, just by looking at them. Of course, there were always discrepancies. Just because someone had a full set of X armor or X weapon didn't necessarily mean they were good; they might have bought runs to get those items, or even bought the account. But nonetheless, it was a way of getting a general idea of how far along in the game someone was, and it was nice to show off your gear with pride.
Of course, you can still show off your gear with pride in the game today. If I had full T16 with a heroic warforged Xal'atoh and Tusks of Mannoroth, then there is no doubt in my mind that I would rock that and show it off in its un-transmogrified glory. From my observations, though, it seems like most players I encounter do transmogrify their gear.
Like I previously stated, I'm not saying transmogrification should be removed. In fact, I don't like the general art direction that MoP went in and I think a lot of my gear looks goofy, so its nice to be able to wear my old T5 set, which is probably one of my favorite sets ever. I just kind of miss the days of being able to look at someone and think, "oh crap, he has full Vengeful, better run".
Does anyone else ever feel this way from time to time or is it just me?