As best I can tell, removing these makes power delivery at part throttle a little more abrupt, leading many to believe that they've magically found more power.
Also, if your secondary throttle position sensor is worn out, the secondaries could start misbehaving and cause some weird issues; removing the plates in this case keeps the secondary throttle system from having any effect. The primary TPS is a well-known issue, of course, but the secondary wears out too.
Personally, I much prefer the bike's better manners with the secondaries in place. You can get back into the power sooner and more smoothly in a corner.
Anyway, in the end it's mostly a matter of personal taste, and it's not a huge difference. Try it and see what you think.
If you'd like to try your bike with secondaries, there are probably hundreds of sets out there that have been tossed into boxes or toolboxes, and they fit into a normal envelope. Post in Parts Wanted and you should be able to score a set cheap.
You'll probably need to visit a real hardware store (not a big box...) to find some M3 screws.
My bike came to me without the secondaries, and it didn't take long to find a set of these. It's the sort of thing lots of riders have lying around, but no one really bothers to put up for sale, so you'll need to ask.
2002 Suzuki DL1000 V-Strom, Dark Metallic Space Blue
1983 Suzuki GS850G, Cosmic Blue
2005 KLR685, Aztec Red - Turd II.2, the ReReTurdening