Even better would be taking the freedom to select the checkbox once the user highlights a certain plugin name. A little aggressive, but serves in a beneficial way, plus, if the user does not want to select multiple plugin at once, he unchecks them.
I wasn’t stating my opinion of what would be best. I was stating what is.
If you feel strongly enough that it would change, you may read our FAQ about making a feature request and follow the instructions there to put a feature request in the right place.
Personally, I feel that either implementation will be equally annoying to a similar-sized subset of the user base. If you’re going to annoy half the users either way, why not just leave it as is. But my stating my opinion in no way prevents you from maintaining your opinion or from making an official feature request.
Addendum: Not everyone uses the mouse for everything, either. Imagine someone who has difficulty using scrollbars with a mouse, so they click on the name of the first plugin in the list, then use arrow keys to scroll down until they find the right plugin. Under the current implementation, they they hit spacebar on only the right plugin to mark the checkbox, and then use TAB or Alt+I to install that one plugin. Under your system, that initial click (and probably every arrow key, because every time you arrow, it highlights the next plugin in exactly the same way a click does) would actually checkmark the plugins as they were trying to navigate to the one they want. Now instead of installing one plugin, choosing Install would actually install at least two (the first, and the one they wanted) and maybe even all the ones in between (if there’s no way to distinguish between clicking on a plugin name and arrowing to a plugin name).