• Steam Is a Port
Steam, the gaming app/service, has a lot of games. It's exciting to see it come to the Mac, and bring great content with it.
But it's obviously a port, and because it does not act like a Mac app. It is frustrating to use and feels cheap.
I've been in a lot of discussions over the last year about showing people things that are new and exciting, and being unafraid to try new interaction models if it's truly a better experience than the default OS behavior. It sounds good in theory, and sometimes it even works in practice.
But I think there are two things that need more ink:
* Your model must be significantly better, not just different for the sake of different, and maybe slightly better sometimes for some people.
* Ports are not exciting new design paradigms. They often represent lazy design and yield poor results. It's technically possible to make a cross-platform app that sings on both Macs and PCs, just like it's possible to flip your company for a billion dollars. But I wouldn't count on it.
Apple has their head on straight with regards to ports. They want apps to be designed with iPads and iPhones in mind. If that means half the apps, that's fine. PC computing never had trouble with sheer numbers of apps, it had trouble with quality. Apple is willing to give up some of the former for a lot of the latter.

Software that clashes with existing UI models exacts a cost on me, the user. It needs to offer a benefit that makes the cost worthwhile. Steam doesn’t.
I mean, you only have to look at Microsoft's built in apps to see that they don't even care about consistency. Steam on the PC is not Windows-like. It does its own thing like more or less every other app.
Plus, I feel that Valve pays attention to overall graphic design of Steam. I find it aesthetically pleasing; it is also consistent with the Steam website. It doesn't feel cheap to mein the slightest, neither on Windows, nor on Mac.
Quite contrary to the main idea of this article, I think it's much more important to have consistency across OSes for apps that might be used by many people (Steam or Creative Suite are good examples). It's much more important that Steam or CS offer me an identical experience no matter what computer (Mac, Win or Linux) is in front of me, than having "default OS behaviour". Which behaviour is not that much different between OSes as people like to pretend, anyway.
The point is, I'm interested in Steam, or Creative Suite, not in Mac Os or windows, whose only purpose should be to support the apps, not to be a matter of interest for me. Steam and CS are the *platforms*, not the OS.
Of course, it's much more useful for Steve to convince people that the best thing is to have a closed, controlled platform with consistent UI.
I think this is a false dichotomy. You can adhere to the conventions of each individual system while still making your application behave consistently across different systems; surely, you are not saying that you would be confused by Steam's Mac version if it used proper Mac window controls on a Macintosh?
Even people who use both, say, a Mac and a Windows computer will expect individual applications to work properly on each operating system. People are perfectly capable of using Microsoft Word on both systems, and apply what they have learned on one to the other, even though Word is a pretty good citizen on both systems and generally does an admirable job adhering to both the Mac's and to Windows's conventions.
CS, on the other hand, is alien both on Macs and on Windows. So while that means that it behaves pretty much exactly the same on both systems, it also means that *everybody* has to learn how it works anew. Learning an entirely alien windowing system with entirely weird controls and internally inconsistent widgets hardly outweighs the advantages that proper Mac and Windows versions would have, except if you're working as a programmer for Adobe, where your main advantage is that you only have to do things once.
In other words, having a version of Photoshop that is a proper Windows application and a version that is a proper Mac application is good for everybody, even for people who use Photoshop on both Macs and Windows PCs.
As an aside, I also suspect that most people use most applications only or mainly on one system, so the people who use something like Photoshop regularly on both a Mac and a Windows PC are probably a tiny minority. Even if some of these people prefer having entirely the same application on both systems, it seems wrong to use this as a reason to force everybody else to use horribly inconsistent applications.
Pathetic really.