As an engineer, there's only one reason I don't want to be on customer calls:

Once a customer knows the person who actually builds the product, they will short cut:

- Customer Service

- Product Management

- Any other sane defenses you put in to protect a developer's time.

And just contact me directly.

Then what do I do to get them off of me without losing a customer?

... That is why engineers don't get on support calls.

If I could be "Anon E. Mouse" for the engagement, that'd be fine. But fact is, that's not what happens.

And from experience, customer requests will not only be pushy and aggressive, but often at odds with company policy and directions. If they have a direct way to contact, one may end up not being able to do one's job due to the interruptions.

personally I think the customers and I both get some value out of our interactions. but I normally don't sit on customer calls. why? because half of the time I screw up the sales aspect by saying

   - the salesperson told you what? no, we don't do anything like that
   - oh, yeah, this is easy, you don't really need our product, just use X
   - yeah, we have vague plans to do that, but no real schedule. its gonna be a major lift
   - once we finish coding and testing that, its gonna be great!

Yes, god forbid that an engineer would be contacted directly to solve a problem they have. The thought alone.