Software encode/decode of JP2k is the hard part. That's why there's little adoption of J2k outside of hardware solutions.
JP2K is still the leader in visual quality per byte. All DCT-based compression systems (jpeg, mpeg, dv, etc) are prone to "mosquito noise" artifacts which are extremely annoying in moving pictures since the noise moves around and looks like mosquitos flying about. The usual workaround for mosquitos is to blur the picture a bit to make it easier to compress; but that softens the edges of object onscreen. Wavelet systems like jp2 suffer from different, less annoying, artifacts.
gzip'ing 4:2:2 is a terrible idea :-). Keep in mind that Jp2K does have a lossless mode which you can use if you really don't want to lose any quality.
The advantage of the wavelet format is that they can implement progressive resolution decoding, so a decoder only needs to read half of the data from a 4K source to decode a full quality 2K image.
But, as always, when you think an engineering decision is insane, you're probably missing the context in which the decision was made.
[1] http://en.wikipedia.org/wiki/Digital_Cinema_Initiatives#Imag...
