If there are actual costs in the form of damage that actually does occur (violating #2), then the landlord has ample grounds to pursue the tenant to recover those costs. People don't get compensated for things that might have happened.
Liability to the government or an injured third-party for events occurring on the property for which liability exists for the landlord and not exclusively the tenant-in-possession; this can exist with no damage to the property.
Further, again, given that the landlord would no doubt charge more for giving the tenant greater discretion to choose what risks to take on behalf of the landlord (even when considering damage to the property alone), breach of contract to take greater risk than is allowed in the contract is a harm to the landlord, because it denies the landlord the opportunity to choose to rent to a different party who would pay for the privilege that the usurping tenant is taking without paying for it. This is a harm that actually happens, not a thing that might have happened.
I don't see how it's the tenant's duty to inform the landlord about the most profitable way to rent out their property. If the landlord wants the opportunity to rent to a different party for a higher amount with more risk, they should go find a different party and make that offer.
Ultimately it's up to the landlord to enforce the terms of the lease. If they aren't going to do it, then they're going to get taken advantage of. If a tenant stops paying rent and you don't evict them, don't complain about not getting your rent. You have a legal remedy available to fix the situation.
If you don't want your property on AirBnB, check AirBnB and make sure it's not there. If landlords started doing that and breaking these leases within the first month or two, this would quickly become unprofitable. They have all the power in this situation.
If the terms of the contract don't sufficiently compensate you when a tenant breaks the lease, change them so that they do. I'm sure plenty of landlords have a story about how they got burned by a poorly worded lease. The smart ones learn from their mistakes and move on.
3. The property is not used in a manner which creates unexpected costs for the landlord aside from the property maintenance issues addressed in #2, such as exposing the property owner to liability it is not prepared for.
(Note that lots of things that can be done with property create potential liability for the landlord and not just the tenant-in-possession.)
> The other terms of the contract are just proxies for achieving those two outcomes. If the tenant delivers on both, they haven't "weaseled out" of anything.
No, in addition to other concerns (like my #3) that you may have forgotten, if the tenant usurps the landlords prerogative of deciding what steps to take to protect the interests the landlord has in the property, the tenant is weaseling out of something. If the tenant wants broader discretion to decide how to achieve the landlords interests without weaseling out of their agreement, they can negotiate that discretion into the lease and pay the landlord whatever premium the landlord demands for that transfer of trust.