I think what @Slind is talking about is changing it so the URL does not appear in full in the HTML version of the email, just the linked title. Not doing away with the link altogether.
It does seem puzzling and suspicious to me to see URLs in emails from the forum that look different when you mouseover the URL.
So yes I would turn off link tracking which stops that issue for right now. That does come with a cost however which is that we can’t track in mandrill who’s opened links. 
We all have to weigh the pros and cons and decide what’s more important… participation or tracking of participation in mandrill. Another trust building effort might be to tell your forum participants to add your forum from address to their contacts to prevent this from happening.
The alternative @slind is suggesting is actually a good one methinks which is to show the title of the topic as a clickable link rather than the URL which is converted by mandrill.
Pity these templates are not user editable.