I don't understand the value of withholding so much information in these previews. If they included the rules to make an entire Level 1 Essentials PC would they lose any sales?
I don't think they would lose any sales if the previews included enough information to make a level 1 PC. I suspect the reason they didn't was because they don't think the changes are as drastic as we do.
Bill Slavicsek and Mike Mearls are game designers. I suspect they change the rules all time, it's their job. Monty Cook once said that he rarely played 3e by the rules, it was his nature to tinker. And let's not forget that Mearls is the guy behind Iron Heroes. So they tinker with the classes and when they find something that's fun and fits with whatever type of product they've planned, they release it. Given that these are variants of familiar classes, they probably didn't expect the level of interest it's generated here.
So when we look the Knight and go "WTF! MBA only and no Dailies?! This is a game changer!" (My personal reaction.) They go "but fighter stances have been out for months, if we can get rid of encounters then eliminating dailies shouldn't be a problem, what's the big deal?"
Also, some of the speculation was starting to solidify as "fact" in people's brains. If this was the typical preview a week or two before the release date, that wouldn't be a huge deal, but a couple of month's out could cause problems.
To the contrary I think more people would be reassured by the extra information and they'd now plan to buy the books.
I agree. I'm posting only to point out that I don't think they expected this level of interest. Essentials has been dominating the 4e forum here. Dark Sun is almost here, and we have two threads about the same preview with over a hundred posts in each. One thread here put "Essentials" in the title even though it has nothing to do with Essentials.
Why is Essentials so interesting around here? Here's why, for over two years, a lot of us assumed that 4e was going to be on the numbered supplement book for a good long while. I was sure that there was going to be a an Arcane Power 2, and Divine Power 2, a Primal Power 2, to go along with Martial Power 2 this year. Until I learned otherwise, I thought that DMG 3 was going to make my September. That perception has changed, however, by the fact that Heroes of the Fall Lands isn't just a reprint book with maybe some new powers. Actually, it started with the announcement that this year's campaign setting is Dark Sun. The the product schedule was filled with Gamma World and Beginner's books.
Now those beginner's books have some great ideas in them. For years, Wizards has been putting out beginner's sets with pre-generated PCs a short adventure, and some rules with short "buy the PHB, DMG, and MM to continue the fun!" and now, that's not the case. And it's very interesting.