It's fun to have a light, snappy bike that fills you with nostalgia for the period when you first started riding without all the downsides bikes from that era possess. Having a race bike with all the aero fixings is great for days where you need to go fast, but for the vast majority of rides -- even for very serious, competitive athletes -- marginal gains don't matter. On those days having a bike that makes you smile is worth infinitely more than 10w in a Tour test.