I suppose "political risk" would be a better term than "legal risk" per se. Subtle differences in the lease and established law increase the risk that the landlord has an unfavorable outcome (possibly including earning potential loss). As a consequence, they are unwilling to consider any changes to the lease, even a minor one, not simply because they may be screwed, but also because there are hundreds of other prospective tenants who would jump at the apartment who won't present them with any such risk.
I suppose "political risk" would be a better term than "legal risk" per se. Subtle differences in the lease and established law increase the risk that the landlord has an unfavorable outcome (possibly including earning potential loss). As a consequence, they are unwilling to consider any changes to the lease, even a minor one, not simply because they may be screwed, but also because there are hundreds of other prospective tenants who would jump at the apartment who won't present them with any such risk.