He said your project was great but will face issues with compatibility. In what universe does that constitute negativity?
Sadly 1.8 definitely won't have a responsive default theme, but I'm sure it's going to happen for 2.0.
I don't know the release plan for 1.8, but I need to get something "now" anyway, so I can't keep on waiting. 2.0 is too far away to be an option.
The only answer I am willing to give for the question: I dislike creating a problem before there is a problem.
Acknowledging a potential issue is not being negative, man. As an aside, you should definitely do what's best for you; Euan is obviously speaking in the context of a general-release project. I certainly know a bit about customizing your site, compatibilities be damned.
However bringing it on this early on a project's life is often unnecessarily depressing and out of scope: it is a thing to acknowledge, but it only matters once everything is almost ready and the project truly is coming out and maintenance becomes an issue.
Compatibility in the other hand is something that can't be properly dealt with: the syntax is so different and MyBB so dependant on specific syntax on many places that it is probably impossible to support but a handful of existing plugins that add template changes. So it is obvious to me that unless people really fall in love with the new theme it is unlikely there will be other support than keeping things up with MyBB's upgrades.
Also as it seems my customization background needs to be made aware: I used to have a seamless design and seamless login integration between phpBB2, WordPress and MediaWiki. I had to unconstruct it once phpBB2 hit EOL and WordPress login integration plugin halted updates immediately after that point. Since then I had a few years I didn't have enough time and energy to do as big customizations or even give my biggest site the attention it deserves. Which is something I've started to fix now that I do have the time and energy.
I've learned this kind of focus on "what is important right now" the hard way and I don't want to waste too much of my energy on things that don't matter right now. Thus while all this is an interesting topic on itself I wish we could keep this thread on the topic that it is about.
As Brad said, I was merely trying to provide an insight into a few of the stumbling blocks you will hit with a project like this. I'm sorry you couldn't take my advice in the way it was intended.
Kuddos to you, Merri for taking on this project. I'm currently working on converting my site's theme to a responsive theme, and it's been an absolute nightmare. I haven't decided yet if that's because of the insane amount of templates that myBB has or because I've taken a lot of liberties in customizing my forum's layout. Either way, great project and glad to see that other people are trying to help myBB head in this direction.
I spent some time customizing theme just like that, but halted as it seemed like jumping straight into swamp. I think isolating to a new syntax while maintaining the original looks will be much cleaner, because then I can customize two of my sites with the same syntax instead of doing it on one site and then recustomizing the customized theme on the other as well. The needs between sites are different and I actually want to remove some stuff from being visible on the first one that stays on second and there would be additions on the first one that shouldn't be on the second and vice versa.
I've already removed a few templates from being used, because they made no sense to keep. I wonder if it would make sense to document and comment the whole "nightmare" as a spreadsheet or something similar so it would be easier to point out the issues.