Yes, it's possible to implement but that defeats the purpose of a tracker. It's important to honor it's heritage, and lots of composers of retro music are used to this way of creating music. If you want bars and blocks there are heaps of great music software available that has it :)
I like the idea. A way to implement this is to allow user to load extra large samples into a separate sample buffer which is not part of the song data, but available to edit in the sampler, so you can copy/cut, add filters and all that jazz. When module is saved that sample buffer is just ignored.