I often think wireless keyboard are for people who casually type while sitting on the couch. Or they sit at a desk and type slowly.
If you type fast, you'll hate wireless keyboards, especially as the batteries start to go. Or in this case, as the power drains from the rechargeable whatever-it-is inside the solar-charged version. The issue at hand is lag. You hit the keys, and there's a delay between your action, and whatever it is you're typing or doing. When you type 75-90+ words per minute (wpm) like I do, you quickly get pissed and want to smash it.
The same is true of wireless mice, which are about as inaccurate as it gets.
Wires give faster response times with less lag. The end.
If wired works, then obey the old rule: If it ain't broke, don't fix it.
That said, I have a wireless keyboard for use with a mini computer plugged into a TV 10 feet away. I also have a mini keyboard with an iPad. I have to go slower when using them. The iPad keyboard is harder to use because it's smaller than normal, so going slow is easy. The big wireless keyboard connected to the TV, however, is easy to overrun. I either wait, or I have butchered text on screen because it missed so many letters.
Honestly, I think a lot of people get wireless devices just because it's the "in" thing. Not because it works better.