Google seem very reticent to show us PageRank, to such an extent that I almost ignore toolbar pagerank at the moment.
Mind you they are not much better when it comes to inward links. I mean can you trust any of the inward link stats that are available from various google locations. They don't even tally one with another.
They actually used to show a breakdown (high, medium, low, and unassigned) of the PR in webmaster tools, but then removed it.
Whenever you have a single number that represents something - IQ, FICO score, BMI, PageRank - everyone and their mother complains up a storm about how the numbers aren't fair (usually because they have a bad number).
Personally I think google is sick of hearing about it, but they really can't get rid of the toolbar pr, but I wouldn't expect them to release any more data on it. It is only one part of the ago - one that confuses 95% of webmasters. If only they had called it BrinRank...
If raw PR is still used in the algo then showing an accurate number (3 significant figures) in WMT would help SEOs backwards engineer it.
The toolbar PR (which displays to 1 sig. fig.) is a pretty useless metric in the grand scheme of things. If you want a single, simple metric to act as a health check then you'd actually be better off looking at the number of root domains linking to your site (which is far from ideal).
>>The reason we all want to see pagerank is to tell how our site(s) are performing
not entirely true, i've no idea what the PR of my sites is, i've never had a PR toolbar installed (well, when the toolbar very first came out i used it briefly for curiosity) the most handy thing about pr is that when i get a link exchange email that mentions pr i just trash it!
The primary reason is that Google does not want to give users their exact methodologies due to more manipulation and having the PR be too accurate would also be too burdensome on the server farms of Google. Google basically changes the PageRank of pages constantly, probably atleast once a week. Their visible PageRank doesn't change until about every quarter because changing that much data based upon the algos not only gives away their true data but also is a HUGE stress to load balancing. Imagine giving trillions of pages constant visible updates to their PRs daily to weekly, EVEN monthly -- it's too difficult.
That doesn't also include the effects of personalization algorithms changing the PR constantly as well as the social graph effects. Lastly, the PR of a page could vary from server to server based upon your location.
The closest server farm to you is serving you your SERPs, the SERPs change almost constantly past page 2 across different areas dependent on where you search.
The reason we all want to see pagerank is to tell how our site(s) are performing,
Not me, I've never taken any notice of it from day 1, I couldn't tell you nor care less what PR any of my sites have. So long as they perform well in all the SERPs that's all that matters...then again, you may disagree:-)
They don't show you PR because it really doesn't matter. Build a site for users.
I haven't checked my site's PR in a looooong time. It's meaningless. My traffic is up and I'm making more cash, I don't care what my PR is on any page I'm responsible for, and I have hundreds (tens of thousands if you include the forums).
Pagerank is still a very important factor for google's search results, there are lots of other factors also, but pagreank is still still nearly the most significant, only preceded by a form of trust rank metric.
That said, the pagerank provided to users is mostly irrelevant, it can be up to a year out of date, and any perceived value from a currently reported high PR url may actually be discounted, devalued or delayed until sufficient trust is gained from the providing and/or the receiving sites. Obviously relevancy is another important factor in the link trust determination.