I can't speak for the developers of ICE, but I can tell you from my knowledge about EXIF why I wouldn't have done it:
A lot of the EXIF information is either related to image dimension or exposure which *must* be changed as part of the stitching process. EXIF information for a stitched image should be a composite of the EXIF information of the individual images. If so,
how should the numerical values be combined? Median? Average? Sum? And for the string values concatenation? Or take the applicable values from one picture only?
For me these are just too many questions with no easy answer. So I would say ICE is not stripping EXIF information as the composite is a *new* image. The developers just opted not to copy anything instead of building a complicated EXIF handler module.