WotC knows players are eager to play their favorites from past editions and they are holding out on some of the games best stuff...on purpose.
If by "on purpose" you mean "with intent to make money by withholding stuff, I don't agree. I mean, obviously it wasn't an accident that the half-orc wasn't included, but I don't think there's the conspiracy that other people see.
The fact is, the books have limited pages. The PHB is actually enormous, when you step back and look at it, and its almost all crunch.
In 3e, adding a new character class to the game generally cost... what, 3 pages? Unless that character class had its own spell list, new character classes were trivially simple to add. 4e uses a different system, in which every class has a power list. Adding a new class takes a certain minimum number of pages, somewhere around... from memory, 12. This means that classes will probably be more rare in the long term than they were in 3e.
So... we have eight classes. They were selected not to fulfill the demands of people steeped in D&D lore and tradition, but rather to provide a relatively even spread of mechanical and thematic aspects without overly multiplying power sources.
Would I like more classes, more races, more feats, more spells, more powers, more paragon paths? Of course I would.
But the PHB does seem complete enough for now. So while I sympathize with fans of half orcs barbarians* who can't play their favorite character types, I don't think its fair to conclude that the PHB is incomplete because that particular pairing is absent, or that WOTC is trying to trick you into buying more material.
*Ok, I'm lying. I've got a friend who loves his half orcs. Basically the only race he plays. And I keep telling him, "Man up! Grow a pair! This is 4e, play a REAL orc!"