What is the purpose of a Suggestions board for a playable alpha?
To collect suggestions. The rest that you said is just your opinion.
You said earlier that Toady "doesn't like being forced or feel pressured to work on things he doesn't want." But then, why have a Suggestions board in the first place?
To make suggestions. And you know, the better UI suggestion already has a topic on this same board. And a item for voting in the Eternal Suggestion Voting. OP was pointed out to it. It is already suggested, discussed and properly answered. If you feel like there's something to add, feel free to join the proper suggestion thread and suggest.
The pressure doesn't come from a suggestion board existing, it comes from people beating a dead horse on duplicated threads, repeating the same arguments. Or from people randomly coming and making a duplicate thread, then some people joining it to beat the dead horse instead of just pointing the person who wants to do the discussion to the already existent thread on the subject.
It isn't as if every single thread is being overrun with complaints about the interface. If they were, I could see your point.
First, because most people and most arguments are already said and the developer already answered. Second, because it doesn't make sense to go shouting "I want a new UI" in every thread, as your extrapolation clearly suggests. Not being discussed in every thread doesn't mean you are not trying to apply pressure nor that the subject isn't talked a lot. By the contrary, the topic is so over-talked that the first answers to the topic are pointing the OP out to the proper thread.
Finally, as long as the conversation is civil - and it mostly has been in this thread - what is the harm in letting people continue to discuss? If the forum staff disagrees, let them handle it, and apply the needed thread locks or user warnings.
Toady and ThreeToe are the forum staff and they are too cool to close threads and hand warnings, so don't expect it to happen. Besides, beating a dead horses and making duplicate threads is not against the rules, it's just extremely bad manners.
The harm is done, as I said, in trying to apply pressure on the developer because you think some things are more important than others, by not discussing the thing in the proper thread. There's already a thread to discuss this, adding what you think to it is fine, but grabbing every thread about the subject to repeat the same arguments is the essence of the "try to apply pressure" and it's just bad manners.
Of course, it can happen of someone making a duplicate thread. That's fine, errors do happen. However one user already pointed out the correct thread (in the second post!) to discuss this issue, so good manners dictate you should go to that thread to discuss this. Preferentially, people should also read the thread to try and not repeat the same arguments again and again just for the sake of you thinking "X is more important than Y and should be done first".