To expand a little bit:
I do not think it's overrated historically. As others have said, position is secondary to being a "great player." if you look at the last 30 years, you have about 5 laker titles, 2 detroit ones, and a later detroit one where the one could very strongly argue that the key player was a PG. Obviously it's very wishy-washy, but some of this can be balanced by the fact that Tony Parker won some finals MVPs, but i'm not counting him at all, so there's some gray area. Additionally, there's some further gray area when things that probably "should" have happened didn't; for example, Joe Johnson's devastating eye injury and the ridiculous suspensions of Amare/Diaw after the Horry cheap shot derailed the very likely NBA champion Suns twice.
So that's 8 titles, approximately, in 30 years led by PGs. Even if we drop it to 6 titles led by pgs, that would be exactly 20% of titles led by PGs. PG is one of 5 positions on the floor, or 20%. So in terms of just titles, I don't think position matters; transcendent talent matters, and that has generally been: Magic (PG), Moses (C), Bird (SF), Isiah (PG), Shaq (C), Duncan (PF), Jordan (SG), Pippen (SF), Olajuwan (C), Wade (SG), Kobe (SG), Garnett (PF), and Nowitzki/James (PF/SF). I see a fairly random spread there.
However, I do think that PG is the most overrated position RIGHT NOW. I think that either there's a talent bubble, or the rule changes have allowed small, quick guys to thrive both by allowing such players to drive without having to worry about bigger guards grabbing them AND having their defensive size disadvantages mitigated by players not being able to use perimeter size/strength advantages as they could in the past. As such, the number of PGs that can put up great numbers and seem like Great players has exploded.
As such, there's a weird era of uncertainty right now. For a while, there was the mantra of "never pass up size," which ended up failing when huge stiffs started being signed way before smaller guys who could play. But now the mantra is "always take the talent," and I really think that there's about to be a reversal of that mindset as it's very easy now to see that some random PG is, in pure thought, a better "player" than many big guys, but such PGs are becoming dime-a-dozen, while talent at some other positions is not increasing at the same rate. If you look back through the recent drafts, you'll see what i mean, and i think a lot of teams will be making big mistakes signing "productive" pg's to big deals when they can get 90% of said production each year in the draft for 10% of the cost and use that money to lock up relatively better (to other players in the league) but "objectively" lesser talent at bigger positions.
Sorry if that is confusing. In other words, yes, you could lock up Rondo at 10 million per year (which i think went from being risky, to bargain, now to hopefully "fair" since there are so many productive PGs), or you could keep cycling in Aaron Brooks, Darren COllision, Jrue Holiday, Ty Lawson types and spend that 50 million on a scarcer position.