The shift to wider bars had certainly taken place by the mid-80s. When I built a "serious racing" bike from scratch then, I followed all the current lore regarding sizing, and for bars that was to get ones measuring about as wide as the distance between one's acromia, the bony protuberances of the scapulae extending out over the shoulders. I ended up with 44 cm Cinelli Campione del Mondos Mod. 66. I still ride 44 cm bars, but I'm happy with 42 too. The bike I had before that was a Schwinn Sierra (bought used) from 1963, and I didn't pay much attention to the bar width. It was a very tall frame, but probably had 38 or 40 cm bars.

Fast forward to the present, and current bars I see people riding seem to be set higher than TdF "style models" back in the day. The drop of bars has decreased a lot (compare Mod. 66 to current "anatomic" ones), with all that kinkiness going on from the ramps on down -- call me old fashioned.

There's a lot of talk about how many hand positions a bar offers. I agree that this is important, but differ from others, perhaps, in how that's achieved. As someone unabashed to acknowledge that I hardly ever use the drops (what the hell are they there for? maybe to hold bar-end shifters), I find that I greatly prefer "criterium" bend bars that slope from tops down to hoods more gradually than most bars. For me, this offers the greatest choice of hand positions -- fingers both wrapped over bar and behind the bar in a couple locations before I get to the hoods. Most of my riding is done with hands close to the hoods, or grasping them. So, I prefer the Cinelli 65, Nitto 155 (rare), and I tried and disliked the Nitto Noodle, which has a kink transition where I like a smooth one.