I Want You was done at least in a short acoustic version:

Besides that and the reasons Seb mentioned, which mostly apply to the tunes of at least HAND onwards, I think it comes down to the band writing quite many songs in their earlier days. Once Jon said "I write all these songs and then forget about them".
Back then they were probably so focused on rehearsing and working out certain tunes for the live shows that track X and Y just went completely off the radar.