There is a famous Tosafot where one of the Tosafists says that Jews shouldnt live in Israel because theyre already weak in other areas of mitzvot - why give them more? This obviously didnt become mainstream Halacha. But my question is why? Isnt it logical to first work on mitzvot youre already obligated in and perfect them, before accepting other mitzvot upon yourself?

ב"ה Shalom, I feel it is a great privilege to answer such a question on Yom Yerushalyim, the day that Yerushalayim , Har Habayit and the Kotel were liberated in the 6 day war by the hands of Hashem carried out by Tzahal. The Mishna in Ketubot (Chapter 13) says that one may compel his family to immigrate to Eretz Yisrael and one may compel their family to ascend to Yerushalayim… First I would like to clarify what is actually said in the Tosafot in Ketubot 110b s.v.:"Hu omer La'a lot…" Tosafot says in the name of Rabbenu Chaim that "now there is no Mitzvah to live in Eretz Yisrael because there are many mitzvot which are connected to Eretz Yisrael and some punishments for which we don't know how to be vigilant …." Secondly, not only is the opinion of Rabbenu Chaim, not mainstream but actually it is in complete disagreement with all the Rishonim: the Rif, Rambam and Rosh who all hold that a husband or wife may force their spouse to go to Eretz Yisrael, even in our time. It is also codified in the Shulchan Aruch (אבן העזר סי' ע"ה:ג) and as the Pitchei Teshuva 75:6 sums up: "all times are equal in to the fulfillment of this mitzvah and this is clear in all the Rishonim and Achronim." This discussion is covered extensively in a book called "מעפר קומי " written by the Kadosh Reb Tzvi Glatt הי"ד who was murdered by terrorists in Chevron. It was just over a week ago on the 17th of Iyyar , we went up to his burial place upon his 41st Yahrzeit. The book was published posthumously and later came out in English "Rise From the Dust". In addition, getting back to the Tosafot again, the Maharit ) שו"ת מהרי"ט חלק ב - יורה דעה סימן כח) writes that the words of Rabbenu Chaim are not from the original Tosafot , but it was added by a student and is totally unreliable. In regard to your question isn't it logical that a person perfect himself in one mitzva before accepting more upon himself, I would have to say that this logic does not apply to keeping mitzvot. I would understand that a Ba'al Teshuva on the path to keeping mitzvot would begin to keep mitzvot gradually until the person learns more how to do things and is ready for keeping all mitzvot spiritually and emotionally. But a person who keeps Torah and mitzvot,, cannot delay keeping Shabbat for example, because he hasn't yet perfected putting on Tefillin. Furthermore, the Chida (יוסף אומץ סי' נב) writes that during the time of Rabbenu Chaim there were lots of unresolved issues in regard Terumot and Ma'aserot, Shemitta etc. and therefore those living in Eretz Yisrael would inevitably have sinned due to these uncertainties. However, the Chida felt that in his time following the rulings of Ramban and Radbaz, these issues were resolved and there is no longer a situation of people not knowing what to do in regard to the mitzvot which are connected to Eretz Yisrael . How much more so in our generation. The Rabbinate of Israel is in charge of all issues of Terumot and Ma'aserot, Shemitta etc.and there is an abundance of sefarim on all these issue,in which all halachot are explained in detail. . This opinion of the Chida is also shared by the Mateh Yoseph (יור"ד סי' ט ) and the Chochmat Adam ((שערי משפטי הארץ פי"א ס"ג. Moreover, I think that what the Maharal wrote (תפארת ישראל פרק ה) in regard to the famous Mishna in Makkot 3:16 also applies here. Rav Chanania ben Akkashia says that Hashem wanted to merit Israel, therefore he gave them a lot of Torah and Mitzvot . The Maharal asks, if Hashem wanted to merit us, shouldn't He have given us less Mitzvot this way we won't do anything wrong if we have to many mitzvot? The Maharal answers, that first of all, the more Mitzvot gives us greater possibilities of gaining more merits following the saying Avot 5 "According to the effort is the reward". Secondly, he says that the Mishna speaks of giving the Mitzvot to the nation of Israel and as a nation we are ready and able to keep all the mitzvot. All the Best. Happy Yom Yerushalayim