I will admit that if it were me buying an i/50 I would prefer easier bias. But as a tube amp owner for over 20 years (all ARC other than an Ampsandsound Nautilus), bias does not normally drift very. much in a stock set of tubes. Everything changes is you swap out tubes. ARC obviously did not bring the i/50 to market for tube-rollers.
With a push-pull pentode design, bias adjustment is vital but again, the consumer could easily get two years of use out of the amp before needing new tubes and bias adjustment. FWIW, my SET HK Citation-based Ampsandsound Nautilus does not offer any bias adjustment whatsoever and does not need it as a matter of circuit implementation. And that is regardless of being able to swap tube types for the power tubes and rectifiers.