With most TVs or even some blu-ray players having the ability to stretch and zoom, why not release them in their original aspect ratio and let the customer press the button to do the cropping automatically? That's the best place to do it and that way everyone who wants the original aspect ratio is happy and those who want it adjusted without the pillarboxing can be happy too.
Stuff filmed in 4:3 often looks laughable when cropped, and there's a reason why directors worked within the 4:3 framing to begin with - not just because it was industry standard at the time.
One example of bucking the trend was the 1983 miniseries "V". Kenneth Johnson kept 16:9 in mind when filming, which is why it translated so well. Now look at the 1984 "The Final Battle" on DVD. Chopped credits and foreheads look skewed. Watch side-by-side with the recent blu-ray release, which restored the full 4:3 ratio, to really see the differences and why resizing it can (but not always) cause problems, but it would cost tons more to go through every single scene cut to reposition properly to re-frame in an aspect ratio that was never intended to be and still sell the full effect, which is why most paraded "16:9" releases just use the cookie cutter method and chop out the top and bottom parts of the image to fit the middle section in indiscriminately. A found a 90s sitcom that had that done - at least their "AI" made the typeface look crisp and sharp, even if it did sod all to the actual videotaped actors and sets, which were still soft - especially when the matting also blows up image size... again, it's laughable...