Rabbi Yosef Shalom Elyashiv is known as the leading halakhist in the Ashkenazi Ultra-Orthodox world. Rami Reiner shows how Rabbi Elyashiv's decisions are hardly ever based on meta-halakhic considerations and suggests that there may be a connection between this curious fact and R. Elyashiv's study of Kabbalah in his earlier years.
[Update: His main thesis is untenable. The Aruch Hashulchan who was very much involved in Kabbalah is also known as one of the greatest meikilim. I do not think the Shulchan Arukh of the Baal HaTanya cotains any major Chumros either. Some of the pesakim he refers to as chumrot are not chumrot at all but simply Halacha (e.g. the issur of the Baalas Teshuva who had sexual relations with a non-Jew to marry a Kohen is a clear Halakha in SA IE:6 - the litmus test of Chumra would come into the requierments for checking this out in individual cases. ). R' Elyashiv generally offers more general, as opposed to case-by-case, rulings in which "meta-halachic" considerations are less likely to come into play.
Regarding contradictions between R' Elyashiv's pesakim, the following anecdote is perhaps a classic example of the cause of this:
Two boys came to R' Elyashiv to ask if one is required to wear a hat during prayer. To one he ruled that he has to wear one, to the other he ruled that it is not necessary. The explanation is that the first boy had been wearing a hat when he went into R' Elyashiv. Clearly this boy believed that a hat is a necessary sign of respect and therefore of necessity he must wear it during prayer. The second was not wearing a hat when he came to ask the question thus demonstrating that he did not believe it was a necessary sign of respect
N.B. I believe I noticed that some of the pesakim that R' Elyashiv issued when he was part of the Beis Din Ha-Gadol together with Chacham Ovadiah and Harav Kappach were republished in a kovetz under R' Elyashiv's name only, but I would need to check again.]