The flexibility thing is just another misconception. There are plenty of strong and flexible people, it goes hand in hand. Go to youtube and check out how sumo wrestlers, power lifters, olympic lifters, and the old school circus strength guys train. You'll be amazed. I doubt most people here have the flexibility to do a legal power squat without any weight, let alone any of the olympic lifts or sumo warm ups.
Strength training has never had a negative effect on my Aikido training, it's only enhanced it. A lot of Aikido students would do well to pick up something heavy and actually learn what physical power is, how it works, and why they can't rely on it in a martial art. They might even stop missing classes or taking half-assed ukemi because their (insert body part here) hurts.
A friend of mine is a massage therapist who works on powerlifters. I think she might disagree with you. While it's *possible* to be both strong and flexible, it requires paying extra attention to mobility and flexibility and a lot of people simply don't bother.
I actually agree with you that strength training can be valuable for aikidoka. Having a strong, stable squat makes a world of difference in koshinage, for instance. I just disagree with the claim I was responding to, that getting stronger is the way to "fix" your aikido.