THe way I see it, the major weakness of the 25-06 is simply in bullet selection.
When you look at the bullet selection available in 6.5mm, it begs the question, why not a better selection in bullets for the 257 which is only 0.007" smaller in diameter then its 6.5mm brother. The simple answer, someone decided that 1-10 and 1-12 twist should be the popular choice for factory rifles. Through the years, the 1-10 twist came out as the industry standard. That should be fine right......
Well, that was fine when the 100 gr spitzer flat base was the commonly used bullet design, now we have boat tail, tipped bullets and even a few with a bit more aggressively designed bullets to jump up BC. In my experience, most of the factory rifles in 25 caliber chamberings prefer 100 gr bullets or lighter for best accuracy. Now some will shoot heavier bullets acceptably well for conventional hunting ranges but I have yet to see a factory rifle really hold the heavy 25 cal bullets into tight groups, that being 1/2 moa for three shots.
Again, the problem, is bullets limited to 120 gr or less and generally 115 gr or less. Why not the 140-142 gr class bullets in 257, again not enough twist rate.
So why not step up to a 1-9 twist, hard headedness I suppose.
With a 1-8 or 1-9 twist, we can easily use 142 custom bullets in the 25 cal rifles and ballistics are dramtically improved. BC of these bullets are higher then what the 6.5mm 140 and 142 gr match bullets can produce and velocity potential would be within 50 fps as well. The 25-06 is plenty of case to drive a 142 gr bullet weight and it would vastly improve the terminal performance of the 25-06, especially at longer ranges and on larger game animal targets.
Its easy to get this with a new barrel and you can turn the 25-06 into something totally different then a factory 25-06. Still, until the industry wakes up, sadly, the 25-06 will be limited in what its potential really should be.
I am not saying its not a potent chambering, far from it, there are new bullets that work well, some better then others but its just not the round it COULD be with the right twist rate barrels.
Until the industry stops looking at the 25-06 as a varmint and light big game rifle and figure out its a legit medium game chambering with the right bullet, nothing will change which is unfortunate.