Very nearly half of HS2 - 64 miles - is in tunnels. This happened because the Conservative government was terrified of upsetting the Conservative voters along the route. The bat tunnel was nuts, but it's not that significant overall.
If they hadn't been so focused on that, they could have built the new rails largely alongside the existing West Coast Main Line which would have been quicker, cheaper and much less controversial.
But because they wanted those very high speeds, the route had to be flatter and straighter than the existing WCML, which means many more tunnels, longer and more complex construction, more people objecting, inconvenienced etc and ultimately much more cost however you look at it.
What I would care about, is the price drop associated with the capacity increase/reduced stress on the existing main line. Not sure if speed factors into that.
I dont care about price as the company pays, but my time is very valuable to me.