If you are following the ideas as put forth by Nitobe, then yes they are highly idealized and romantic. One might argue (and several have) that Nitobe was just about the worst person to write a historically accurate work on the ideals of the warrior class. He was very much a product of the race to modernize Japan, was educated overseas at the university level (first in the US, rather unsuccessfully and then later in Germany), spent years and years abroad and was a Quaker which he converted to by though his American wife's influence and he felt that there was a strong similarity to his Quaker faith and the ideals of the Japanese warrior and his faith colored much about how he viewed Japan.
During his uni days in Germany, one of his teachers asked him were the Japanese got their moral values from, since religion and morality were not subjects covered in the Japanese school system at that time. Nitobe had no answer to this question and supposedly it bothered him for many years. Much later in the later half of his life, he spent a chunk of time in California (if I recall correctly) while trying to recover from some illness and it was during this period of down time (somewhere between 6 months and a year again if memory serves me) that he decided to try and address the question and write the book "Bushido". The book was originally written in English for a Western audience and only later was it translated into Japanese and gained fame there.
The fact of the matter is that there was never really any single defined "bushido" at any point in Japanese history (at least until World War Two anyways). The closest things we can probably find are various documents surviving in the records of various domains with "pointers" on how warriors of said domain were expected to live, but these all vary radically from each other and were very much subject to the whims of the lord, etc writing them. Many of the works famous now (Hagakure comes to mind) only achieved their fame much later and their influence around the time of their writing tended to be minimal and/or local.
Surely, such noble thoughts have been present also in traditional bushido, through the ages, but aikido refines them and comes with new, surprising solutions.
Regarding the refining and surprising solutions, I thought that for many years as well, but the longer I spend in Japan doing the research I am doing, the more it seems to me that Ueshiba was just recycling things that had been floating around for centuries before. While I wouldn't say said ideas were completely commonplace, there were a number of ryu that did carry the philosophy to equal extremes and, in some cases I think, much more elegantly than the somewhat haphazard situation that is Aikido (I have no doubt Ueshiba was a man of gifts such that we rarely see, but in many areas he was obviously winging it). It's to the point these days where outside of some of the Omoto-kyo stuff, I don't really see much of anything original in what he brought to the table. Not that that makes the pursuit any less worthwhile of course....
Hmmm, did I stir the pot enough there?