Well, if a safety case can be made then we can replace class E with class D or even C and job done. But not only would that upset a lot of users who would have to upgrade their kit to continue to use airspace that they have always operated in, it would also require more resources for ATC to deal with the extra workload. It also would not stop the occasional glider or puddle jumper from blundering into controlled airspace anyway.
I expect the class of each area of airspace is under ongoing review that attempts to balance public safety with access. Seems to me the best thing is to just get on with mandating ADS-B as a requisite for all aircraft that wish to use class E. But it still won't stop infringers.
This incident should also serve as a reminder to all pilots that they have a responsibility to look out at all times when VMC regardless of whether they are IFR or VFR, being vectored, or getting a separation service.