Why are hidden things bad? Well, there are different kinds of hidden things. Some are bad and some are good.
There are things that are hidden to prevent damage from being done to innocents. Potentially dangerous things are concealed from those who would misuse them through lack of knowledge and skill, or those who would deliberately misuse them. Those include hiding dangerous things away from small children, and hiding information that could be used to harm people who have done no wrong away from those who would do wrong (say, hiding personal and confidential information secure from crackers and marketing goons).
There are the things that are hidden to prevent damage from being done to guilty parties. Who killed JFK. Who left the slugs in the hall. These are largely hidings of deeds and evidence, evasions of responsibility. There are some instances, surely, where this might be the only humane thing to do (such as the literary Cordelia Naismith's defence of the mad and loyal Constantine Bothari's version of justice), but by and large, I don't approve of it.
"I wonder why Dad is so thoroughly mad", Jack Prelutsky
I wonder why Dad is so thoroughly mad,
I can’t understand it at all,
unless it’s the bee still afloat in his tea
or his underwear, pinned to the wall.
Perhaps it’s the dye on his favorite tie,
or the mousetrap that snapped in his shoe,
or the pipefull of gum that he found with his thumb,
or the toilet, sealed tightly with glue.
It can’t be the bread crumbled up in his bed,
or the slugs someone left in the hall,
I wonder why Dad is so thoroughly mad,
I can’t understand it at all.
There are good things that are hidden to be revealed with proper timing. Holiday presents. Happy surprises. Good information that has hierarchial issues (one tends to tell the immediate family and friends first of an engagement). Some good things wouldn't have half as much impact, or be half as delightful, without concealment to aid in the effect.
There are good things that are hidden away, not to be revealed. This is often wasteful of the good thing in question. However, much of the stuff that's treated this way is treated so to keep harm from being done to it by those who would unknowingly or deliberately misuse it.
Finally, there are those things that are not deliberately hidden, just overlooked, or not discovered yet. The usual reasons are overfamiliarity, not seeing that which is hidden in plain sight, and underfamiliarity, the "Oh, I didn't know it was possible...!". Reasons for not looking further into things include lack of resources, lack of interest, the thought that it might uncover danger/unpleasantness. Probably more.
Friendship is an interesting thing. Everyone meets people, and gets to know them a little. Some people are asshats, some people are saints, and most people are somewhere in the middle.
One person's approaching-asshat may be another's approaching-saint, of course. That's just the way it works. Different values, different tastes, different styles, different priorities, and lots of miscommunications.
Thing is, when someone's discovering themself, and what their values and priorities are, they're going to find that around them, perhaps in some of the people they thought they treasured the most, are conflicting values, opposing priorities. The other parties may be perfectly OK people, just not suited to the newly-defined priorities of the one. Should the one have children, and the one's friends wind up to be toxically rabid childfree advocates or even college students uninterested in the whole domesticity thing, there will likely be some parting of ways, amicable or not.
The first acquaintances to go if the one is uncovering the hidden areas of oneself are typically the ones least open to change, the ones only attached shallowly.
As one becomes more familiar with the self, and with others, the nature of friendship becomes more clear. Are the friends really the sort of friend who would come over at midnight with cause? If not, is that OK? Are the friends the sort that one would not wish to come over at all? Are those friends OK with that?
Unequal loyalty is betrayal in the egg. (Thank you, cantankerous Ista.)