That can happen. Never mind why. Discussing that won't fix your house.
If you have more damage costs, then you must have higher repar estimates. If you have higher repair estimates, you need a re-inspection.
If you need a re-inspection in connection with higher written repair estimates, calmly and politely call "CLAIMS" and request instructions on how to submit a "POLITE" letter to the claims department employees. Those employees that did not incorrectly inspect your house are there to help you. Explain your dilemma. Ask for a re-inspection by a qualified "Allstate Claims Adjuster". You possibly were inspected by a contracted inspector anyway.
Before you do this, you be sure you are dealing with an honest contractor. Have more than one estimate done to be sure you are not being used by a dishonest contractor. Once you are confident you require a re-inspection, make the selected contractor commit to being on site for the re-inspection.
If everything is under-estimated and you do this, you will be taken care of..... Past experience say's so. This is standard procedure.
Get it done.