It is certainly more practical to learn speech without writing in Japanese than it is in, say, Latin or ancient Greek. It’s a bit of an onus getting anyone to chat to you in Latin these days as in vocal chatting using the mouth rather than a keyboard, whereas writing is a breeze as they’ve got the American alphabet. If you can say it, you can write it.
Japanese can be written in Romaji (literally “Roman letters” but of course they mean American ones, really). For Russians there is also a version of Rosjiaji which is commonly seen in sushi restaurant signs and menues in Moscow. You get the Japanese in cyrillics but they write “si” for “shi” and “va” for “wa”, which is a bit annoying. There are much more annoying things than that in Moscow, though. Just try and buy a burial plot and you’ll know what I mean. For Hebrew letter transliteration, they even have Jumanji, named in honour of the comedian Robin Williams.
So a good idea is to take Japanese in four or five stages, firstly do a bit with audio only using like a Pimsleur course and then do the grammar all through one time just with transliterated writing in your own alphabet. Then the second pass is to do that whole thing over once again but with the Japanese writing hiragana instead of Roumaji, Jumanji, etc, and then the third is to introduce katakana where it is appropriate. The final stage is to bring in the actually Kanji – so-called because you need a real can-do mentality to get through them. These are the Chinese symbols which refer to whole words but unlike in Chinese they may have one, two, or multiple readings or even be part of special “ateji” constructions (so-called because you probably won’t believe this) where the usual readings have nothing to do with how it gets pronounced in one particular special combination with another symbol.
Even speaking Japanese and using Romaji only is not exactly a keiki-wouku – you have plenty of complexity such as the fact that men and women use different words and different syntax, there are potentative verbs, verbal pairs for transitive and intransitives and the forms are not generally predictable or even memorable, there are benefactive verbs that describe the direction of benefit that practically need to be paraphrased when translated into other languages, and there is Keigo, or polite language, which is made up of using verbs and nouns which elevate the other person and his or her circle which being humble about one’s own uchi set, ie. one’s person, one’s own belongings and one’s family or team. You can of course learn Japanese at a level where the nuances of polite language are ignored and you just use -masu forms to everyone, but in certain company that is just going to make you sound like a fairy.
Given that real mastery of Japanese even at a spoken level only is such a tricky business, one may as well do the extra work and not go to the trouble of learning a challenging language but still looking like a functional illiterate. There is more fascination in the Kanji, which have a long history often better prerved in the Japanese forms than in the revised forms used in China today. Learning the Kanji gives you a unique jump off point into learning one or more of the Chinese languages.