First, this may well be overridden by the individual rights of present patients (see proposition arguments).  Second, the greater time taken to recruit is one that may be offset by greater numbers: whilst the trial will be of a lower quality (no control group, etc.) there will nevertheless be a greater number of people willing to take the drug (people who wouldn’t have wanted to be part of a trial, but are willing to try the new treatment). Consequently, it may well be possible to compensate for the other problems with the trial. Further, alternative trialling models can be employed, for example using patients who choose not to take the drug as the control group. Whilst you lose the benefit here of having a double-blind trial (as under the status quo), you gain in terms of the benefits to current patients.