Just because you don't use a feature or don't like it, doesn't make it useless, or stupid. Everyone's experiences vary and we make mistakes assuming that one's expirience is the same as everyone else's.
I've found that my ability to find an app has increased quite a bit with the new method. With the horizontally paginated drawer, it would take several swipes to get to the page that I thought the app was on, and I often had to scroll back. I can find, say, Play Movies, with a flick and a touch or two where before, I had to flip, flip, flip... etc.
The search function... I completely disagree about it being useless. I've been using the search feature on windows for a while now... "Windows Key + Wo" will get me to Word in considerably less time than finding an icon on the desktop (which would require me to close/minimize windows to see it in the first place). Using the above Zedge example... long press drawer button then 'Z' once it loads... there's Zedge (along with Zillow and Zooper for that matter). Plus in addition to that, If I wanted to download a new weather app, all I need to do is swipe out 'weather' then clock 'Search for more apps" and it brings me a Google app search that has quick links to the install page for the found apps.
Another big improvement is that this new vertical scroll approach was extended to the Widgets selector on the homescreen. I always found the horizontally scrolled pages clunky and slow and difficult to navigate. The new approach is, for me, a lot more user friendly... scroll quick to the widget app you want and it has a sliding list of the app's supported widgets.
The changes Google made there were all in the name of usability. You might not agree with the changes, and you aren't alone. But there are quite a few people that would disagree with you (including the only ones that matter - Google). I've been running the M Previews on my Nexus 6 since they were released, and these new UI changes are one of many reasons why I've stuck with the preview and remained on 6.0. Now that they've trickled down to the other versions, I might have gone back to 5.1.1 (well, maybe not since the full release of 6.0 is right around the corner). Last time I used a phone with the older method, I found it tedious and frustratinging slow.
But, as someone mentioned, it's Android... so if you don't like the way it works, there is nothing to stop you from loading a launcher that will change the behavior to your liking.