Tanned/pale skin is easily obtainable, the former in just a few minutes on a sunny day.
I think you'd be surprised to discover how many people have issues with tanning and how much of a process it is for them. Many people suffer from sunburns in attempts to tan and end up having to use a controlled environment like a tanning bed to carefully not overdo it. Some people just don't get that tanned from the sun at all. And even if it isn't an issue, the average modern human's daily life demotes noticeable tanning (from an already less pale complexion) so in a way, in places like the US it can show that you have a lot of free time to potentially be going to the beach and whatnot as opposed to working in an office all day (and even if you're not going to the beach and all that, faking it can provide a similar impression towards people subconsciously)
In south Asia, for example, fair skin is very desirable but blonde/red/auburn hair isn't. Perhaps the odd highlight but not total Scandinavian blonde!
I think the culture ultimately defines what trends are actually selected, so blonde hair might not become a trend there, but the bottom line is society will by nature find challenges collectively to use as a "trend" to see who can play the game of fit in and who can't. If the culture won't allow it then it likely can't become a trend.
Well, conformism doesn't always mean conforming to the most conformable social standard; it often deals with conforming to standards that are difficult or even nearly impossible to achieve

which is usually what leads to the sticking out in the first place (the nails sticking out being mainly those who don't bother trying to participate in the trend, at the expense of being outcast)
And for the record I think most of the time, whoever is swinging that hammer ends up knocking the nails out of the hole when they're sticking out, rather than hammering them down

I have hardly ever seen a case of a "stuck out nail" being successfully hammered down into conformity, usually they just completely separate from the entire construct