How wonderful it would be if all speakers were easy to drive and possessed of high sensitivity, and less power would get us all by. But it seems to me that what some folks are conveniently overlooking in their romantic reveries about the 'golden age' is that most speakers partnered with the lower-powered amps available back then simply could not deliver either the frequency or amplitude bandwidths along with the low distortion, even dispersion, and flat response that we demand from modern speakers. You can't have it all in a speaker design, and I for one will gladly accept the 'moderate' efficiency of most modern speaker designs in exchange for their now-commonplace combination of neutrality, extension, high S/N ratio, smooth power response, dynamic range, and freedom from resonance and breakup effects.
I am not in this hobby in order to pursue any slightly fetishistic agenda pertaining to certain schools of thought concerning equipment design, comfortable nostalgia, or the self-consciously iconoclastic exclusivity of belonging to some tiny 'club' whose members are more discerning than thou. I just want to hear more of the music and less of the means by which it is reproduced. I am well aware of the general lack of correlation between rated amplifier power output and sound quality, but that works both ways - there are many audiophiles who, while professing agreement with that last statement as it applies to lower-powered amps, seem to take it as a matter of faith that there will be a (negative) correlation between sound quality and rated watts in the case of higher-powered amps. Untrue. Low power is no guarantee of superior sound, and high power is no guarantee of either inferior or superior sound. All other things being equal, if a higher-powered design were to envince no overall sacrifice in sound quality at low-to-moderate listening volumes or playing delicate music versus a lower-powered design, I would take the higher-powered option for its predictable superiority at higher listening volumes or with the most demanding material (disregarding for the moment such practical concerns as purchase price, heat production, power consumption, and size and weight).
If it were indeed true as some would have us believe, that there exists a low-powered amp 'sound' and a high-powered amp 'sound', then both of those supposed identifiably different 'sounds' would represent deviations from the truth, and as such the goal should be to engineer amps that don't impose those characteristic deviations or limitations upon the sound (within, of course, the hierarchy of real-world constraints alluded to above). If that goal can be met with greater rather than lesser available power, then there should be no reasons other than the aforesaid practical ones why that capability should not be offered.
And maybe that's just what has happened. Maybe when people talk of 'convergence', what they're really saying is that today, you don't necessarily need to sacrifice anything desirable of your 40w to get your 150w, practical issues aside. And if today's better speaker designs - which most audiophiles will agree are capable of superior all-around performance compared to just about anything comparable available 20 years ago - can make good use of that power, then it is entirely justified. I've lived happily with under 50w, and know I could have been happy with even less if I owned different speakers. But now that I'm in a house with a larger listening room rather than an apartment with a small one, I'm getting even better sound by using 4X the power, and can still bump up against the system's dynamic limitations if I so choose. To those who would advise me to learn to listen at quieter levels I say, I often do - but feel the parameter of amplitudinal fidelity is too often overlooked by audiophiles focused on other (also worthy) sonic qualities, or understandably compromised by various real-world restrictions. But to me, the problem of reproducing recorded piano at a realistic volume without difficulty is just as important as are the challenges entailed in playback which strives to optimize any of the other well-known audiophile wish-list qualities (and probably more important than many).
As Schubertmaniac's list makes clear, maybe we are not losing anything - even for the money (adjusting for inflation) - in today's relatively higher-powered amplifier universe, and really have nothing to complain about (especially considering the modern plethora of SET's available for those who want). It's just possible. And if true, then the seemingly irrefutable evidence concerning the minimal sales of the smallest and least expensive audiophile models (speaking now of conventional SS designs) is completely understandable, as is any manufacturer's decision to either drop or phase those models upward to a higher power plateau.