Because there are pro's and con's of the amp and you've only stated some! Some people would prefer a tiny amp like the pico while others would like a Talucent, just for IEMs! Heck I never need 80hrs of run time because I have a habit to charge all my gadgets each night! And we aren't even talking to those who use an amp for a 32ohm TF10 vs those who use a clip zip for the TF10! Everyone has their preferences! If size/battery life/power was an issue, why bother with an...
The E12 gets glorious reviews from users of in-ears and heapdhones, it has power to drive a TF10 or future purchases, it is well built, it is backed by a big company and you know they will be there, looks totally slick, decently affordable... Why would you dismiss the E12 when looking for a portable amp?
I just love the stock cup's more understated appeal with the subtle gold prints on it. The aftermarket cups just shows-off that wooden grain too much and doesn't feel as 'connected' to the rest of the headphone, if you get what I mean.
Guess what? Do-it-yourself and check the difference out. And if it doesn't improve anything? You've learnt to appreciate another well-thought out element that the Sennheiser engineers have put into this product.
I think while forums are open to opinions, people on average appreciate politeness. Your first post could definitely have used a lighter tone e.g. 'Wow that's expensive... I would've gone for a D5000 instead but congratulations for your new purchase" that kind of comment would have had the same effect and not left another headfier unhappy for the day. With that money however, I would also gone for a D5000 XD