When looking at these discussions I'm always surprised at how low expectations some people have on their Märklin-stuff. And then again, maybe my expectations are too high...
I personally think the durability of the Märklin trains have gone down during the last few years. In part that's due to more advanced electronics and more detail. You can't argue against that. But I also think it's due to quality (-assurance) problems. (Hmmm... I might have mentioned this before.

)
And I do believe that Märklin intends to, and will, get past these problems sooner or later.
If this actually is the case, it wouldn't be so strange. Purchasers desperately hunting for lower costs often leads to quality issues if someone isn't around to check that what you buy meets the required standard.
I can't help sharing with you a story about the swedish (quality) maker of lawnmowers (yes, lawnmowers

).
A couple of years ago a purchaser found that you could buy engines really cheap in China (were else...). So he bought thousands of them, got a fat bonus and was promoted. But no one seemed to care about the quality. At least no one made extensive tests of the engine. After all, it was
CHEAP!
Now this company is left with a really hurt brand name and TONS of complaints. And guess what! It's very hard to get spareparts from the engine-manufacturer in China...
Maybe this story isn't directly transferable to Märklin, but at Stummis forum I've read that Mr Pluta has questioned many invoices from suppliers on ground that the delivered goods was faulty or not up to standard. So I think that there at least could be some similarities.
And are they toys or collectables? As we can see above they can of course be both, depending on the item and the person who buys them. And I guess we all somehow "play" with our trains.
But that said, I think they
very often are collectables or at least
advanced toys. And, as I've said in some other posts, I do think Märklins way of promoting their stuff (shop-in-shop, wording in catalogues) implies that they themselves think their products (at least most of) are more than "merely" toys to play around with. I think they have gone towards more detail in the models to please those who collect rather than those who play.
But these are my thoughts, and as we see many thinks otherwise. It would have been interesting to see some kind of survey on what the "average Märklinist" expects from his/her products. Maybe such a survey is the first thing the new owners of Märklin should put their money in.
/Torbjörn