The Arizal says that techeiles only applies during the days of the Bais Hamikdahs. Rav Elyashev shlita wrote a lengthy, as-yet unpublished teshuva (as far as I know) about today’s techeiles to Rav Feivel Cohen, explaining at leangth why we do not use it. The Arizal is one of the reasons he brings.
The Arizal is difficult to understand: what does the bais hamikdash have to do with techeiles? There is an explanation on this by the Satmar Rav ZTL: Chazal say that the value of the techeiles color is that “techeiles is similar to the sea, which is similar to the sky, which is similar to Hashem’s throne of glory.” But Chazal also say that “since the Bais Hamikdash was destroyed, the sky has not been seen in its pure color”. Ergo: Techeiles is no longer “similar to the sky” and therefore no longer similar to Hashems “throne of glory” after the churban.
As for the YU rabbis and the rest, Rav Elyashev said they’re wrong. And he, being much greater than all of those Rabbis, says its useless to wear the Techeiles, meaning, no, don’t follow their example.
For the record, one of those modern rabbis is going around dismissing the Arizal because some sages in the Gemora after the churban worse techeiles. The fact that they use such reasoning – that the Arizal doesnt count based on what you see in the Gemora – is itself a reason not to follow them. We cant dismiss the words of the Arizal because we think we know better. Just because they cant think of an asnwer to the Arizal doesnt mean someone else cant. Bishvil kushya lo yishtaneh hadin – the Halachah doesnt change because you dont understand it.
(And even were we to accept their challenge to the Arizal, it is satisfactorily answered, as per above. So no more problem with the Arizal and the Gemora.)
Rav Shach ZTL writes regarding a certain issue, that if the Chazon Ish didnt think there is any reason to do it, and that doing it doesn’t benefit you in any way, someone who thinks he knows better “needs bedikah”. The same thing applies here. If Rav Elyashev, after hearing the case for techeiles, said theres no reason to wear it, and more, that we should not, because Klall Yisroel throughout the generations apprently ruled like the Arizal, then we dont do it. (And its not as if these rabbis have any reason why we should not follow the Arizal – as I said, their “problem” with the Gemora is quite answerable).
If you want chumras, the Chazon Ish has a strong case for prohibiting using nails in your sukkah; a strong case exists for not opening and closing your refrigerator on shabbos; some people hold you are not allwoed to wear glasses outdoors on shabbos.
If you really want to take on an important halachic behavior, follow Rabbeinu Tam’s shitah of Motzoi Shabbos – there you have the majority of Rishonim, plus the shulchan aruch, holding that if you end shabbos with the “early zman” you are a mechalel shabbos.
Let’s get a perspective here.
If you want to take on chumras, at least take on those which make much more halachic sense. A good way to tell which are which, is to follow the lead of the great Gedolei Yisroel, those with the proper Yiras Shamayim and Torah perspective. And thats excactly what Rav Elyashev is saying — believe me, he is more religious than you or I, and he is much more careful about violating and minotiry shitos. This techeiles thing was not taken seriously by the overwhelming majority of our leaders. If you want to take on chumras, start with those that are not really chumras – first get rid of your kulos; then take on the chumras that are more halachicly weighty than this.
Here is a small, starting-out “Action plan” for you of behaviors that are more halachicly well-founded than the case for Techeiles. Some of them are things that you should actually be doing, as oppsoed to relying on minority opinions or precarious heteirim. Others are things that we apprently should be doing, but we dont simply because of historical precedent, even though we dont clearly understand the heter not to; still others are the opinions of some poskim, while others disagree.
1) Wait 72 minutes before you end Shabbos
2) Dont eat chodosh
3) Dont let your wife wear transparent stockings
4) Do Birkas Kohanim every day, even in Chutz Laaretz
5) Do hagbaah before leining also
6) Wash for a davar shetivulo b’mashkeh
7) Specifically designate 2 witnesses by the badeken, like you do under the chupah
8) Wear a talis, even if you are not married
9) Dont use nails to support the walls of your sukkah
10) Dont let anybody Jewish use your credit card except you
11) Dont return something to a Jewish vendor for a refund, even if it was bought with a satisfaction-guaranteed, money-back deal.
12) In fact, dont even buy something with a 30-day (or whatever) satisfaction guaranteed or your money back deal.
My list is only the beginning, only a small moshol. We’re talking about an entire lifestyle that you are not living. Unless, you are one of the Gedolie Hador, and even then, Rav Elyashev doesnt think the case for techeiles is valid enough for him to worry about it.