I said earlier in this thread the appeal of Ps are obvious, but I'm going to disagree with everyone that says you NEED to own one. Its pick up and play nature makes it an easy choice for most genres and styles of music, but the same can be achieved with most decently built basses although additional knob playing may be required. Of course if you know your instrument this is something that merely takes seconds.
Anyway my point is there's no such thing as a must have bass. You can make most basses work for everything. Whether you can or not depends on you, the player.
First, play the bass you love. If you don't like a P-bass, then pay no attention to these missives. Nothing wrong with that.
But nothing sounds like a P-bass unless it has a righteous P-bass pickup in it, and has the woods like a p-bass as well. Many efforts later, ask me how I know...
By "righteous," I mean that not all P-pickups sound the same. some are more P-like than others. for my money, Fender's CS 62 is the best.
But saying one can make any bass sound like a P is like saying one can make any bass sound like any other bass just by fooling around with the EQ. It ain't so. Try making a P sound like an Alembic. or , especially, vice versa. Saying this displays a lack of understanding of how basses produce their sound, particularly pickup design and placement, and wood tonal effects on everything.
As for everyone owning one, I think that depends on how much of one's life is devoted to bass, and how many basses you plan to own. My life has ended up pretty much devoted to it (pro player, music school, the works), hence my opinion. For the weekend warrior, hell no. Play what you like and be damned with the rest. People have families and expenses and the last thing I'd suggest is that baby go without shoes so a P-Bass can sit unplayed in the closet. For those who own a gazillion Jazz basses and the plethora of high-end distillations (you know who you are) I'd suggest adding a lowly P to the collection. and play it. however, stopping by a music store and playing one for a little while to get the feel of it and the sound of it is fun. then hang it back on the wall and say, "OK, done that." Know, however, that properly set up, a P-bass can have a super low action and play like buttah. You will probably not encounter this in a music store.
As with all things, nothing is written in stone. Is the P-bass the be-all and end-all? no. I just believe that it's an important instrument, is far from overrated, and is probably the most versatile of all basses. Armed with a really good Precision Bass and a likewise-good Jazz Bass, there's nothing one can't do.