No matter the channel, it is routed through CRM software and is tagged with your status. Phone calls can be best used to resolve a problem which can be fixed. But, BA won't change its boarding process because of a call. On the other hand, if 15% of the passengers on your flight complain about the same thing, e.g. boarding issues, it all filters through the system and change might (I stress might) happen.
Cut and paste is the way of the world. Best way to send in a comment is to focus on the one thing which was important to you and make that comment no more than 2-3 declarative sentences. That way, the agent scanning these, who likely has 30-40 seconds to generate a stock response, can focus on something you consider important.
If you think it's "petty" it is definitionally "petty" and you should ignore it and BA will too!