We hear this concern but - IMO, there is nuance here. CU15 will release this CY; that will give you lots of time to get to "Exchange SE equivalent" testing in your organization. Indeed, there are still SUs that we will release, but we release SUs when needed; there could be an SU immediately after Exchange SE RTM, for example (and before CU1).
The issue here is that we still release updates (usually SUs) with regressions. This is a problem that we have done a lot of work on and have added to variety of testing scenarios and improvements. But issues still happen. We realize that "release quality" (particularly for SUs) is something that we must do better on.