Because the team needs to learn to win. Regular losing is likely to cause frustration among players, coaches, FO, and ownership, and likely to lead to knee jerk reactions and large scale changes. It's not like we are in the first year of a rebuild (we are in the second year of the nth rebuild). Fans have been sold a certain dream, and it's quite likely that the ownership and FO believed in that. This does not mean making the playoffs, but certainly progress towards that goal, ultimately reflected in the W column will be important. It will be all the more critical this year, since we don't have a draft pick next year.
A team as young as ours is expected to improve significantly. Multiple young players saw significant time last year, and are expected to be much better this year. Not all of them will pan out of course, but if even some show some improvement, team shall be much improved. Add a high pick, and Giles, who has been sold as all that and more, and fans are right to be excited, particularly long suffering ones as us. If the team shows little progress, it might cause some heads to roll, and the resulting instability is something we can ill afford.