The common law with regard to Landlord or Tenant liability for defects in the premises is well established. The Landlord is liable for dangerous conditions which are known to the Landlord but not disclosed to the Tenant. The Landlord is also liable for dangerous conditions which the Landlord could have learned by the exercise of proper care and diligence. In fact, the Landlord is considered to have "constructive knowledge" of a dangerous condition where it can be shown that the condition occurred with regularity and was therefore foreseeable. The Landlord has a duty to reasonably inspect the premises before allowing the Tenant to take possession, and to make the repairs necessary to transfer a reasonably safe dwelling unit to the Tenant unless defects are waived by the Tenant.
On the other hand, the Tenant is held responsible for dangers existing prior to the lease and which were obvious or which should have been discovered upon reasonable investigation by the Tenant. In other words, the Landlord has no duty to advise a Tenant of a condition which is readily apparent.
Finally, when the Tenant accepts the rental premises, the Tenant does not relieve the Landlord of his responsibility to disclose (or repair) defects that are "latent" (hidden) and could not have been discovered by a reasonably careful inspection.
This optional section probably does not change the rights and duties of the Landlord and Tenant with respect to each other, whether or not it is included. However, including the section serves to highlight the respective duties of the parties and serves as an educational and informational tool. Landlords will want to include this section because it notifies the Tenant of what the Landlord is not responsible for. Tenants may choose not to include this section, even though including it probably does not alter their legal relationship with the Landlord.