You start with "Personally, I would prefer subreddits," but then you describe nothing that would be easier or better in a subreddit than it would be in /r/discussion/ with a tag. Well, there is one exception to what I just said: subreddits are easier for a user to understand if the user is impatient with the considerations behind the design of software and the design of online conversations.
But there are very strong reasons why some of us advocate tags -- and why tags have increased in use -- even though the resulting software is more difficult to understand than older designs were, so I would ask you to make an effort to understand the solution proposed by Tricycle.
Note that I am not affiliated with Tricycle. I have never even had a conversation or a correspondence with anyone at Tricycle.
Now that I think about it, I agree with you. I think in the above post I had in mind that subreddits would allow more "cohesiveness" or a greater "sense of community" among its participants. But perhaps that is nonsense or not so important.
However, which "very strong reasons" did you have in mind? I can think of only two:
1) If there were multiple subreddits, often a post might not fit squarely in a single one.
2) People might tag their posts in subreddits anyways, in which case why have subreddits?
A while back, I polled the community on the possibility of subreddits. Most people said they wanted them, and I said I'd investigate.
I talked to a couple of people and eventually ended up talking to Tricycle, the developers of this site. They told me about their own proposed solution to the community organization problem, which is this new Discussion section. They said that searching the discussion section by tag was equivalent to a sub-reddit. For example, if you want a sub-reddit on consciousness, the discussion consciousness tag search is an amazing imitation
I told them I wasn't entirely convinced by this and sent some reasons why, but I haven't heard back from them lately and I'm not going keep pursuing this and make a big deal of it unless a large percentage of the people who wanted sub-reddits are unsatisfied.