I can think of several reasons why I might be unhappy to have the links to my website from yours include utm parameters that you have chosen for me:

• You don't know how I set up my other campaigns. Your choices for campaign name and source are unlikely to match what I use in other places. It will add noise to my Google Analytics campaign report
• I would expect that organic referrals would appear in the referrals section of Google Analytics. When you add campaign tracking, they appear under campaigns instead. I wouldn't expect any non-paid traffic to appear there.
• Googlebot may not be able to assign link juice from your site to mine properly because the links are not to their canonical form.

I can think of several reasons why I might be unhappy to have the links to my website from yours include utm parameters that you have chosen for me:

• You don't know how I set up my other campaigns. Your choices for campaign name and source are unlikely to match what I use in other places. It will add noise to my Google Analytics campaign report
• I would expect that organic referrals would appear in the referrals section of Google Analytics. When you add campaign tracking, they appear under campaigns instead. I wouldn't expect any non-paid traffic to appear there.
• Googlebot may not be able to assign link juice from your site to mine properly because the links are not in their canonical form.