It's about the forum showing up on an cellphone or tablet. The people who link here have changed what kind of electronic device they are using. I still use a net book but many are switching to tablets and phones. The internet originally was set up for simple near monochrome display but as competition and tech got more intense it seemed we really pushed display and visuals to an extreme.
Goes to all those old threads stating "56K dial up slow loading" in the day, remember? Well, moving into phones did the same thing, mobile electronics couldn't handle the huge amount of display and it slowed down page loading. When you are looking at a small 4" screen, things get horribly cluttered, and the mobile services were translating a lot of the visuals by stripping out certain features. That introduces more delays and errors.
If we want fast loading and a clean look on phones and tablets, we need to have fast loading clean pages to work with. A lot of web sites are transitioning to mobile friendly software because of this. It's not just this site, it's industry wide. Phones are driving the change. Desktops and laptops are fading away as the primary display.
That might be overly simple for the guys working the levers behind the scenes, but it should give an idea what's up.
And there is also the fact the old software was prone to hacking, which caused a big scene a few months back when thousands - literally thousands - of websites went down due to an attack. Old outdated software isn't such a good thing in today's internet.
And yes, there are a few tweaks needed, the reply box is a bit indistinct. Doesn't seem to stop us tho.