I totally agree. A 24-105/4 was one of the first lenses I bought when I switched to Sony four years ago. Makes a decent one-lens walkabout kit and covers everything from wide scenics and interiors to tight portraits. It was, for me, a dual-use lens for both my paid event work (lit group portraits) and my walkabout scenic adventures.
But, I ditched it this summer. I strongly prefer more reach for walkabout, and after considering a 28-200, I went, instead for a 20-40 & 50-300 combo, as this is still very portable and I can combine the 20-40 with my 35-150 for event work.
If there were a decent, smaller 28-135/3.5-5.6 for under $700, I might be interested.
IMO there are three basic issues, and all really come down to person preferences and tolerances:
(1) Are you willing to carry more than one lens and swap lenses in the field?
To me, as an amateur, the answer the large majority of the time is no. So whatever the merits of the 20-40mm + 50-300mm combo (or anything like that, e.g. 16-35 + 70-200mm), the two lenses are not satisfactory for me. But obviously you and many others disagree. There's more than one reasonable personal preference!
(2) What range of focal lengths do you think you really need or at least want?
Again that is highly personal, depending on what you shoot and how you like to shoot it. But to me, I strongly prefer having the range of
at least FF equivalent of 28-85mm, and find 24mm quite useful. After 85mm I see somewhat diminishing but still substantial use for 105mm and even 135mm. That's based on having had as my standard zoom at various times various lenses starting at (or equivalent to) 24, 28, and 35mm, and going to 77, 80, 85, and 105mm. I found 35mm really just not wide enough; 28mm was usually wide enough, but not rarely I wanted wider. I found 77 and 80mm often not quite as long as I wanted; 85mm was better, 105mm better still, and I think I'd find 135mm even better yet.
(3) How much loss of optical performance, lens speed, weight / size handiness, and/or money are you willing to tolerate?
Most zoom lenses of more than about 4x or arguably even 3x have substantially worse optical performance than lenses with lower zoom ratios. Most lenses with large zoom ratios are slower at the long end. And then there's weight and cost.
So all things considered, I find the Sony 24-105mm f/4 a very good compromise for my needs. Before that I had an APS-C camera and a 16-50mm f/2.8 lens, so equivalent to a 25-77mm f/4.3. I found equivalents of 25mm and f/4.3 okay, but 77mm a bit short. That lens in turn replaced an 18-50mm f/2.8, so equivalent to a 28-77mm f/4.3, and I found equivalent of 28mm not wide enough in addition to 77mm not long enough. Going back through a bunch of lenses over many years, the only one that rarely left me thinking I didn't have long enough was a 35-105mm f/3.5-4.5 (on 35mm film); and the first one that rarely left me thinking I didn't have wide enough was the 16-50mm / 24mm FF equivalent. If my "walkabout" were e.g. Manhattan, then I'd be coveting the 20-70mm. But mostly I'm quite happy with the 24-105mm.
Of course, this is all so very personal, YMMV, and it's nice to have so many reasonable choices!
P.S.
Minolta made an
AF 28-135mm f/4-4.5 that was (I guess is) very well regarded, but it's about 750g (and A-mount, and screw-drive, and ...). Maybe one day you'll get what you want.