The plugin manager has become like the staff view, which are two areas suffering neglect. (This BTW is not to start an argument on the staff view)
The plugin manager needs refining to make it scan faster and the GUI needs some thought as well, it has been the same for multiple editions going back years. It is all well and good supplying new plugins and content through the membership model; but it would be far more appreciated if you looked at something as basic as the plugin manager and its performance.

Mine will scan a good portion of my plugs the spit a string of cascading "buffer overflow" errors like solitaire cards in windows. Must have come across something it didn't like do doubt, but they're just vsts right? Could be more robust I agree. Your plugs are very important, second only to recorded tracks.
 
The good thing is is that I see all the plugs I expect to be using and don't know if any are missing so I don't fret about it.

Not sure what you are referring to. The *only* purpose of plugin manager is to create plugin layouts today.
What needs refining? VST scan on the other hand has been updated in every version and is the fastest in the industry since the scan is done in the background and seamlessly. 

The plug in manager and VST scanning have improved by leaps and bounds since X1 or prior. No complaints here.

There are two programs discussed here, the plug-in manager and the vst scanner. The scanner has gone through considerable rewrite and optimization. I have the scanner set to "Automatic Background Scan" and the process takes less than 2 seconds to scan 781 plug-ins. Not a record plug-in count but I would guess more than average. If the scanner takes excessively long to complete, may want to review the scan path and options in Preferences > File > VST Settings. I rarely have need to look at the plug-in manager.
 
Edit: I figured this would get a comment from Noel given the time spent on developing the scanner.

You do want to make sure you don't have 146 VST folders listed as places to scan on 14 different drives 
 
I also don't see any need to do anything to the plug-in manager. I use it to create layouts, then I forget about it unless I need to configure a plug-in as a synth or something.

I don't know of a case since X3 where a plug-in needs to be forced to a synth. The plug-in options screen which has the option is available in the VST2/3 drop down in the plug-in header.
 
Aside from layouts, excluding plug-ins is the only time I use the plug-in manager. I know some use it to rename plug-ins but I avoid using that function.

The only thing I would like to see in the Plugin Manager is an option to select ProChannel plugins in the left screen and allow the creation of a menu in the right screen as per other plugins. Just so I don't have to have a giant list with icons that scrolls off the page when viewing the ProChannel Insert Module option

But that's a new feature not a gripe.

The plugin manager does need some love - full drag and drop of plugins across the whole window would be helpful, and showing more details in the list rather than just a name would also be beneficial. But for me the main issue I have is that of tracking new plugins - I can't see at a glance which plugins aren't included in the current menu configuration, which means that when Sonar discovers new plugins (as it often seems to do these days after an update), I have no idea what they are or how to get them into my menus. FL Studio has/had a solution to the latter - after a scan finds new plugins, they show up as red in the list for the rest of that session, so you know they're new. But there are potential other alternatives - be able to list plugins by when they were first found, or last updated, have an 'all other plugins' option on a layout that shows any that aren't already in the layout, etc.

What would be really cool is if you could say, right click on an effect in the insert effect menu and "send it to" a plug-in layout folder. That would make me just giddy. Gimmie access to the source and I'll do it for ya out of the goodness of my heart! :-)
 
I run exclusively from a layout of go-to plugs to speed workflow, all in nice folders by type. When I get a new plug I have to first, set my view to all plugs, then go find the plug in question. If it rocks then I want to just send it to the say, flanger folder of my pet layout. But I have to then enter the manage layouts section.
 
Switching between my everyday layout to all plugs then back to my layout seems like a lot of steps to just check out a new plug for those of us who use layouts.
 
Maybe there could be a "recent plug" like the recent dowloads in FireFox. When you download in the most recent versions and click the download arrow on thfe title bar it smartly only shows the file you just downloaded rather than the whole download folder sorted God know which way.
 
Sorry I went off :-)