Is it appropriate to write RIP for expressing grief? [closed]

I came to this question after I saw a Facebook post about someone who passed away with everyone posting rip as a comment. Wikipedia tells me the following about the abbreviation of RIP:

"Rest in peace" (Latin: Requiescat in pace) is a short epitaph or idiomatic expression wishing eternal rest and peace to someone who has died. The expression typically appears on headstones, often abbreviated as "RIP".

Possibly it is just me, but is it really appropriate to write RIP to express grief? It seems not decent to use an abbreviation in this case—is there not enough time to write it at least out?

Granted, after all the three letters do not root from modern age and internet like LOL, but have a historic background, plus it eases international verbal communication as it is with the word OK.

I wouldn't really consider this an expression of grief. Rather, I'd consider it an abbreviated gesture of respect.

If a close friend or relative dies, I feel grief. I might be shocked, saddened, and moved to tears. I might feel angry about the death. I might feel distracted by the loss. These are all manifestations of grief.

On the other hand, if a celebrity dies – someone I may have heard of, but was never personally acquainted with – I might pause for a moment and think of the contributions that individual made to society at large, or to their profession. In that case, RIP serves as a closing thought, a benediction of sorts. Obviously, RIP stands for "Rest in peace," but in that context, it could be regarded as shorthand for a slightly lengthier, "May he rest in peace."

On headstones, RIP has been the usual form for centuries, given the limitations of stonecarving. It's slightly more respectful in typing to use R.I.P. (e.g. here), but either way is perfectly acceptable. I would never use rip myself, but in the right context it would at least show sympathy.

Feeling grief is a personal thing. Different people express their grief different ways. Some like to do it openly, while others might withdraw and do it in private. Some feel grief without mourning, some mourn without feeling grief; some shed tears, some lament, some pray, etc.

When it comes to RIP, it's commonly used on headstones and doesn't really express grief but rather is a sign of respect and sympathy. That said, I have seen the the abbreviation used on various internet forums and social networking websites. In emails and messages it's commonly used after the main message, similar to email signatures.