Personally, I feel people are too reliant on Tolkien for their Elf designs, and I would personally encourage experimentation.
Agreed. This is one of the things I love about The Elder Scrolls (well, mosty Skyrim). The faces of Mer -- particularly the Altmer -- are different from human faces. They usually have more defined cheekbones and chins, and tend to have slanted and/or almond-shaped eyes. They look alien.
Speaking broadly I'd quite like to see elves that didn't have the pointy ears. Wouldn't fit DA of course, since "knife ear" and "flat ear" are part of the setting, .
I mean, there's nothing in LotR or the Hobbit which says elves have pointy ears. It's vaguely suggested in some of Tolkien's other writings, but clearly not especially important.
Why can't elves be defined by their immortality and affinity to magic, rather than physical differences?
Pointy ears have pretty much become a given trait of elves. If you tried to create elves like the one you propose, people would be all, "So, they're magic humans, then?" If it doesn't have pointy ears, it's not an elf as far as most people (myself included) are concerned.