You are exactly right. I believe it also goes beyond that -- they didn't want to give communities the incentive to wait for a disaster to make improvements, thinking 'if we get hit, then we'll make improvements'. You want communities to make those investments for themselves, not rely on the federal government to do it for them.
The reason that places like Texas and Florida bounce back so quickly is that they've made those investments. Both areas have strict building codes, especially in coastal areas. Texas, for example, spent billions hardening it's electrical grid after Ike, and Harris County (Houston) has spent billions on flood control and mitigation. They have shelters, staged equipment, redundant communication systems, and contingency plans in place. Houston is even changing these to require all new construction to be 2 feet above the 500 year floodplain. You want communities to make those hard decisions and investments, so that disasters don't have as significant an impact. Contrast that to places like New Orleans with Katrina and Puerto Rico. Both communities knew they were vulnerable, and failed their citizens miserably. We want to encourage cities to be prepared like Houston and Miami, not helpless like New Orleans and San Juan.
The flip side of the Stafford Act is that it allows a framework for the federal government to help communities recover, without waiting for specific legislation. FEMA is able to have a system in place, and communities can know the requirements and be prepared. For example, Houston had an agreement with an audit firm to monitor and report on the massive removal of storm debris. Roads were cleared immediately with municipal crews and contracted help from private companies. You heard very little about this effort because they had a system to follow and a plan in place to do it. The Stafford Act isn't perfect, but it's a great benefit to affected communities.
When it comes to long term investment to spend federal dollars to upgrade infrastructure, we should have a separate debate and legislation -- whether it be upgrading the levees in New Orleans or the water treatment plants in San Juan.