I think the answers to why we see less individuality and fewer "original type personalities" amongst apostolic preachers today lie more within the apostolic movement than outside. There is NO DOUBT at all but what the earlier generations were born at a time when there was much hardship. Many were born into and came out of poverty. Hardship tends to make people more resilient and tough out of necessity
There also was much less of a herd mentality within the OP movement back in the early days. It was much smaller back in the day when men like CB Dudley, Verbal Bean, Shue, Pugh, and some of the others who've been mentioned got saved and called into ministry.
Many of the men we think of were 1st generation OPs and the effect that comes with being 3rd, 4th and even 5th didn't touch them as it effects OPs today.
They were originals and didn't have anyone much to pattern themselves after. They were who they were - such as they were - and were tutelaged for the most part by the Holy Ghost.
Our Bible schools have churned out many many preachers over the last few decades. They pattern themselves after their mentors and leaders, develop the same preaching styles and have been encouraged to all think and believe and do things the same way.
There's a herd mentality within the OP movement and the cookie cutter dynamic is huge.
I listen to a lot of these guys and they all sound the same. Not saying that's necessarily a bad thing but many of them are just kind of bland and blah for the most part. Anointing minimizes the bland/blah-ness - thank God for that - but even anointing is scarce with a lot of these guys. In my opinion.
I grew up around preachers who I think for the most part were individuals and rough hewn kind of guys. RG Priest, Allison Post, CB Dudley, Wynn Stairs, Bill Drost, Paul MacDonald ........ etc. These men were strong, tough ....... definitely individuals who weren't afraid to stand up for what they believed .... even when or if it went against the status quo.
But I expect the younger guys today growing up in the church and perhaps later entering the ministry will say the same of some of us.