Well, depending on how an arranged marriage takes place there is still a lot of decision making based on emotions. True there are some very cut and dry arrangements, but even then there is a risk that someone would not be deemed a good enough match. That's a very common complaint, especially among younger men who perhaps did not appreciate just how much value the families of potential matches would place on their chosen degree.
Or indeed you may find those they think are good matches for you are not at all to your taste. I've known more than one person reel from the discovery that the very good match their parents had decided upon was not at all to their aesthetic tastes, but the very, very real comment given to some of them was that if they wanted better matches they needed to be a better match. But of course these people have had more of a choice than others. Some turn up, see the match is not with someone they would have wanted, and have no choice but to proceed.
Besides, arranged marriages do not remove decisions made on hormones and emotions alone. It just means those decisions are made with greater secrecy, and in some cases mean you have more to lose if such things became public knowledge.
Re: age gap arrangements. It does not matter so much, it is an arrangement and if it is arranged well then the age difference is of little concern. In some cases it would be preferred as the older the gentleman in the match the more likely it is that he fits the criteria of being a good match. A younger man may be more of a gamble, he has potential but will he fulfil it?
However you roll the dice, there are complexities and frustrations.