I think you should be comparing it to if the other option was to record the land or building as a regular PPE.
If regular PPE, your options are the cost model or the revaluation model.
If investment property, your options are the cost model or the fair value model.
Strengths of investment property (if it can be applied):
The key difference would be if applying the fair value model vs the revaluation model.
With the fair value model, you do not have to take depreciation because the whole point is that this land or building is being used to earn rental income/capital appreciation so it's not being "used" like a regular piece of PPE and thus no need to depreciate. This will result in lower expenses and a higher net income, which is a strength.
I believe that with the fair value model, any increase or decrease in fair value hits the P+L versus with the revaluation model any increases go to OCI (which is separate from net income) and any decreases do hit the P+L. So, assuming an increase in fair value, it is much more beneficial to have the fair value model of the investment property standard because you can benefit from the increase to income from a gain in value and the balance sheet value of the asset is increased as well without having a corresponding increase in future depreciation expense (since no depreciation expense under the fair value model).
In general, if comparing to the cost model, the main benefit is that you are going to be showing investors a more accurate picture of what the value of these properties truly are. However it is obviously time consuming, costly, and more complex to revise the values based on fair values because fair values may not be readily apparent. The cost model is very simple because you never touch the original cost (aside from taking your depreciation).