That would be less valuable than other studies. DART with Dimorphos is one data point, to gain enough knowledge of the problem space to be able to build actual asteroid diversion systems based on the principle would require a lot more data points (realistically dozens). We need to understand the variations of how rubble pile asteroids are built, the range of possible impact dynamics, and what levels of predictability can be expected along with what features and measurable aspects can be relied on to guide that predictability. It may be that the next rubble pile asteroid we try to do this with is twice as effective, or half as effective, or maybe not effective at all, we don't have that data yet. DART is really just the first step of a long journey towards building the technology of asteroid diversion, and it is also not the only way to do it. It's a technique that will work in some situations but not others.

A lot of people imagine DART as being like this prototype of a system that we can just pull off the shelf and use to save humanity, but it's just basic research into the problem space, it's nowhere near anything like a prototype.