Uncompressed 24-bit 1080p running at 24 FPS requires 1.192 Gbit/s, or 0.149 GByte/s. So a 25 GB (single-layer) blu-ray has enough space for a whopping 167.8 seconds of uncompressed 1080p video running at 24 FPS. You can double that with a dual-layer blu-ray, and there are more corners you can cut, but I don't think you'll fit your movie in there.

Video is really big. Compression was needed to make it even vaguely possible unless your quality was in the toilet.

HD-DVDs were smaller, so they were more compressed.