The point I'm trying to make here is, again, look at all the teams that have picked a top-5 pick during the last 30 years. That's 150 picks.
Now, how many times has being one of the teams that was bad enough to earn one of those picks directly helped that team (participation or trade) to a title within some reasonable time-frame (say, within 10 years)?
The point you're making is that getting a top 5 pick is not a sufficient condition for winning a title, or even getting a really good player.
Still, it's a bit of a weak point, I'd say, because there are 30 teams in the league, and only one team wins a title in any given season. So obviously the number of teams that fall short over any given era, and given any particular type of roster construction strategy, is going to far outnumber the teams that manage to win a title.
Personally I look at it more the way that IP does -- make a list of the very best teams in the league at any given time and ask yourself how those teams acquired their best 3-5 players. Far more often than not, a top 5-10 lottery pick plays a major role in acquiring top talent.
I do think it's important to keep in mind that getting a top pick isn't the answer to everything. It doesn't solve all of your problems. But it is the easiest way to get a really talented player on your team and under your control for an extended period of time, and once you get one or two top level talents, it makes everything else that you try to do in order to build a competitive roster much easier.
I agree with you that not getting a pick that falls in the top 5 wouldn't be the end of the world. There are plenty of examples of players taken in the 5-12 range who are very good, and there are almost always gems even outside of that range. The draft isn't the only way to acquire a top player, either.
I've said it many times, though -- ending up with a pick at the end of the lottery, or just outside of the lottery, after enduring a losing season like this one, would be disappointing on a number of levels.