Commentary for Kiddushin 120:12

The dispute is placed in case of “from today and after death” to let you know that even in this case Rabbi considers it a condition and therefore she is divorced. Had we taught the dispute in the case of “on condition” we might have thought that only in that case does Rabbi hold that she is divorced, but not in a case of “from today and after death.”

The Talmud asks why not teach the dispute in the case of “on condition” and from here we could learn that even in this case the rabbis are not sure what he means and therefore she is only doubtfully divorced. All the more so we would know that in their opinion she is doubtfully divorced if he says “from today and after death.”
The answer is that it is better to frame the dispute in a way that we can see just how lenient Rabbi is—in both cases we hold that she is divorced. It is better to teach a leniency because it takes greater halakhic boldness to teach leniencies than stringencies.