Ticketing systems tend to increase in price over time. I know one nameless company looking to migrate after their current system increased in price. Open source isn't any cheaper, you still have to pay admins.

Though one other reason to migrate is the forms are complex and full of required fields nobody understands. Migration will get you past that to what matters, but only for a few years before the groups that required those fields in the first place come back and demand it with the same good but forgotten reasoning as the first time. If this is you, get your act together.

I’ll just let the execs know that we should not allow ourselves to be acquired again, will I?

Every company larger than 50 eng I worked for had at least one ticket system migration.