Ray wasn't a screw-up, but he displayed signs of self-destructiveness and didn't do all that well when he dove into new things head first -- even Steve said Ray was "much too vulnerable."
I don't think Ray was a screw up either; his problem was he lacked self-esteem. It was that lack of self-esteem (no doubt caused by spending his formative years being known as the son of the town drunk) that made him impulsive when it came to business decisions. He was so eager to prove himself - to show that he could do more than be a ranch foreman - that he couldn't wait for Jock and Punk to get back home to do another real-estate deal with them. He'd had two successful deals with them and had he waited for Punk Anderson to begin another real estate deal, I think he could have done well. Had he had a sold sense of self-esteem, he would have waited to learn more about the business before going into a deal on his own.
Had Ray had a solid sense of self-esteem, then when he decided he wanted to try to do something new and Donna responded with "Where's that cowboy I married" Ray would have had the strength to say "I'll always be a cowboy but I'm not going to always just be a cowboy. You're just going to have to accept that I don't want to be limited to doing only one thing anymore than you'd like it."
It would have been interesting to see some type of storyline regarding Ray's self-esteem, where with Punk Anderson in a bigger role as Ray's mentor, Ray gradually goes through a growing process where he learns to build his self-esteem by learning how to do new things that would interest him. Personal growth is a tough process because you're going to make mistakes along the way, and some of those mistakes are going to be painful. That's why a lot of people don't get involved in personal growth. But as Punk Anderson once said: "We all make mistakes - that's how we learn"!
Watching Ray go through that type of personal development would have been great to watch and I think it would have been rewarding for Steve Kanaly to go through an inspiring type of long term storyline like that with an arc to it where he goes from being a man with low self-esteem to a man with much greater self-esteem. A nice benefit of that would be that his marriage to Donna improves because he now feels good enough about himself that he no longer has any fear that Donna is outshining him.
It would have been better if Donna had encouraged him to take that approach to life as opposed to trying to always try to talk him into staying "that cowboy I married." Donna said it herself in one episode around the time when they were breaking up: "People grow or they die"! She was talking about herself of course, and her need to keep trying to new career paths. It reveals a lot about her character that she would say that and mean it, yet always try to keep Ray from taking chances by trying something new. Doesn't "People grow or they die" include Ray too? Instead of protecting him from making mistakes - and "protecting" him from learning and growing too, I would have liked to see her encourage Ray to do things he expressed an interest in doing and in doing so let him know that she believed he had great potential, instead of sending the message "You're a cowboy; that's your place - the only place you'll ever belong." That's a destructive message for her to send to Ray because there's a heavy implication: I can to anything I want but you're not very capable and you'll just get hurt if you venture outside "your place in life." Besides, it's almost guaranteed to result in impulsive, ultimately self-destructive behavior coming from his desperate need to prove himself and now, his desire to prove her wrong!
Rather than send that destructive type of message, she should have been encouraging him, acknowledging that there are certain things he's got to do if he's going to feel good about himself. Besides, their marriage would always be troubled as long as Ray had a low self-opinion. The constructive way of reacting to Ray's interests in doing new things would have been to tell him that if he wants to try that, great, but try it in a way that's most likely to end up successfully. If he talks about doing something impulsive, emphasize the value in waiting to learn more from Punk Anderson first, that ambition is great, but rushing into things half-assed isn't ever a good idea. Emphasize that he has more to learn before he embarks on a solo venture and that's not a slight on his abilities; it's a sincere desire for him to succeed at whatever it is he wants to do.
I think that if the show had taken Ray's character, as well as the dynamics of Ray and Donna's marriage, in that direction, that there is a great story there to be told which would have been very satisfying for the audience as well as giving Steve Kanaly something it seems he was looking for - new directions for his character and the challenge it would present him to portray Ray doing that and doing it convincingly.