"In that price range why could it not be an extra in the box?"
Have you seen how much a fully-pimped Mac Pro costs these days? (Remember: you have to buy a screen for those too!)
And why don't you make the same argument about cars too? £9K for a small cheap car, but a decent audio system costs a whopping £350 extra? "Leather effect" seats adds £1K! Electrically adjustable wing mirrors? Certainly sir! That'll be just £450+VAT!
If every f*cker else can—and does—do this, and Apple have never been an exception. Even Dell and HP will nickel-and-dime you when they've a mind to. As will Adobe. And Microsoft. ("Oh, you want that feature? You'll have to buy the Pro Edition then! That'll be another £100 please!)
It has built-in WiFi—and Apple kit supports the 5GHz band too, not just the cheap seats. It has a bloody PCI bus on a string port. Twice! It even has USB 3 and an HDMI port and an SD card reader.
No, it doesn't have an optical drive—big whoop; sales of MacBook Airs haven't exactly suffered, and OS X has supported optical drive sharing at the EFI BIOS level for years now.
No, it doesn't have an Ethernet port as standard either. So what? You're already splashing out the best part of £2K on the machine; is a £25 optional extra really such a bummer? It's not as if you'd notice the weight in your laptop bag. After all, if weight were really such a priority, you'd have gone for the MacBook Air instead.
Also, the term "professional", in this context, is NOT limited solely to "programmers and IT admins". GbE is useless for me when I'm working on video projects. Dumping the file out to a nice Thunderbolt (or, hell, even USB 3!) external hard drive gets the file copied a bloody sight quicker than dribbling it over a GbE wire to a NAS drive when I need to do some archiving.
Stop acting like your profession is the only one that exists.