If you have practice many types of falls in jujitsu then you also have seen the practice focus upon slamming the opponent to the mat, this is not the focus of Aikido practice ... although as you become more skilled, it can be.
The variety of falling from ukemi in most Aikido practice throws allows for the the slight diversion of anglular throws to allow for rolling rather than dumping you partner on their head. Unlike the gentler angles of Aikido, the uncontroled falling that sometimes is found in many jujitsu throws can cause injury over time ... even if the fall is interrupted or broken by correct breakfalls the force can overcome the level of safety.
Funny how a slight change of angle can make falling easy or hard?
With this level of safety for practice in mind to the degree of danger, Aikido doesn't create a need for breaking your fall as often as is needed for rougher more uncontroled falls created in some jujitsu techniques.
I have crashed to the ground in many different uncontroled positions. I do encourage practitioners to study the different ways other arts encourage you to learn how to fall ... it becomes unneccesary in the most Aikido practice. I don't think it is due to the capability of Aikido to not contain the capacity to inflict physical damage, but that practitioners exert a conscious effort to practice within nonviolent and safe practice standards.
I can't say you will never again use the many positions of falls you have learned in jujitsu breakfalls, but to roll and recover from some of the breakfalls onto your feet again is much too difficult to do in Aikido practice.
Breakfalls suggest what they are named for, breaking the force of your fall to the ground without injury.
On the other hand, ukemi is the ability to take a technique or fall into the most advantageous position to recovery.
Would you rather fall and struggle to regain your footing, or would you rather blend and take technique into a more advantageous position? Bounce and recover as it were?
It isn't so much that learning different falls is ignored, but that the falls we use in Aikido are directed to having the practitioner learn to turn adversity into a greater advantage than breakfalls.