Why are some live TV plugins located on the client and not on the TVserver?

Are you talking about LogoManager plugin or what?
Since Logo files are stored on client in Mediaportal TV Engine This plugin is operating on client.

 

Logos could be delivered from the server and cached on the client. Personally I would prefer this architecture.

In my opinion a better reason to have the logo plugin on the client side is that the client's "style" (skin etc.) may vary. Different style logos are needed for different style skins. This is something that is more difficult to handle for a server-side plugin. It isn't impossible to handle... but I did not design/create the logo manager plugin.

 

My opinion is that downloading logos from server is unnessesary use of bandwith that could interfere tv vieving

 

There are design trade-offs with both approaches. This consequence seems very unlikely, especially if the download is handled properly (ie. in an asynchronous background thread with lowest possible priority). On the other hand, a certain consequence of having the plugin on the client side is that it must be installed and configured for each client installation.

You are one of the plugin developers, so you get to make the choices. Hopefully you consider the opinions of other people such as lodale...

[edit: I would also add that recording thumbnails are stored on the server and cached on each client. The same approach could be applied for logos... if you wanted it.]