Mask off completely and just make it completely usage based for everyone. You could do something for trial users like first 20 (pick your number here) requests are free if you really need to in order to get people on board. Or you could do tiered pricing like first 20 free, next 200 for X rate, next 200 for X*1.25 rate, and then for really high usage users charge the full cost to make up for their extreme patterns. With this they can still subsidize for the people who stay lower on usage rates for market share. Of course you can replace 200 requests with just token usage if that makes sense but I'm sure they can do the math to make it work with request limits if they work hard enough.
Offer better than open-router pricing and that keeps people in your system instead of reaching for 3rd party tools.
If your tool is that good, even with usage based it will get users. The issue is all the providers are both subsidizing users to get market share, but also trying to prohibit bad actors and the most egregious usage patterns. The only way this 100% becomes a non-issue is usage based for everything with no entry fee.
But this also hurts some who pay a subscription but DONT use enough to account for the usage based fees. So some sales people probably don't like that option either. It also makes it easier for people to shop around instead of feeling stuck for a month or two since most people don't want multiple subs at once.