Why this is not done automatically or at least given an option to do so?

You've got plenty of options for magnet links in Tixati. First add trackers to a torrent, then select the torrent and go to Options > Meta-Info tab. Here you can choose from some preset list of trackers. Additionally you can customize how a magnet link created from the context menu will look like. Go to Settings > Transfers > Meta-Info, look for a text field called "Magnet link formats for transfers pop-up menu". There you can specifically set what format will be used for the context menu (right click a transfer > Share > Copy Magnet Link). I don't remember what are the defaults, adding [tracker] placeholder at the end should work.

Thanks, that worked but there isn't any way to copy multiple trackers, is there?

Maybe go to settings/transfers/ trackers and see if that suits your needs.

If you have a problem with tixati not copying tracker(s), go to Settings > Transfers > Meta-Info and in "Magnet link formats for transfer popup menu" add &tr=[tracker] to the end of the code.
If you want to copy more than one tracker, add &tr=[tracker] for the number of trackers you have.
Ex. 12 trackers -> copy the &tr=[tracker] 12 times like so:
magnet:?xt=urn:btih:[hash]&dn=[name]&xl=[bytes]&fc=[files]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]&tr=[tracker]