Gerardo, I think that your statement is comprehensive and I agree with almost all of it. I, for instance, enjoy sweeping before class, and have been missing it because of my situation at work. (It didn't occur to me until yesterday that I could do my part *after* class, which is what I'll be doing from now on.) Likewise, starting class together, warming up together, following the thread of sensei's instruction together: all of these are important and desirable.
So, please forgive me if I single draw attention to the one item which I tripped over as I read your post:
Many dedicated aikidoka run businesses, have demanding jobs, or have become parents. Their situations sometimes demand changes in the way they attend aikido class. It is the right thing, I feel, to understand and support people in such difficult situations.
* People who are late for Saturday/Sunday morning classes… what possible excuse can they have?
I don't know if you have ever worked shift work, nights and weekends. I do. Although it's rare that it interferes with getting to Saturday morning class on time, sometimes it does.
If we would judge, we should investigate. Remember that we probably don't have all the facts, even if we perceive a pattern, so it is courteous and proper to inquire before we critique.
I personally feel that aikido instruction is a privilege I am given in exchange for respect and commitment, and part of this commitment includes making a sincere effort to be on time for class.
As an aside to Aikido students generally, when you must be late, you can treat it as an opportunity to blend in a different way. There are many ways to attract sensei's attention, bow in, and stretch out. See if you can join the class and get up to speed with the courtesy, awareness and economy of motion which you strive for as you practice. Because of my recent situation where I must choose between arriving late or not practicing, I have had the opportunity to study how to blend in this way, and I have found it a worthwhile study.