People knew about Titanfall and were waiting for it for at least a year before that. The new pricing was only known about if you were paying attention that day AND didn't already have an X1 but yet cared enough about gaming that it made you need one just for $100 discount.
It shows also that there isn't really any significant number of people who wanted an XB1 (the type of people who would have known about this price-drop announcement first) but were just waiting for a price cut as they deemed it too expensive currently.
The unfortunate thing about the price-cut is the timing of it. Again, it is a little MS shooting themselves in the foot for the umpteenth time.
June is not a good time for a price cut because it is a slow sales month. It is even worse timing when there is no notable Xbone software coming in June or even the next few months.
What MS needed to be was really bold if they wanted to catch the PS4. A price-cut in March to co-incide with TF would have had a significant impact.
Instead they were overly bullish about the prospects and effect of TF on hardware sales. It didn't do anything on its own but would have in conjunction with a cut to the system price.
Now what they are left with is a price cut whose effect is likely to get lost in the slow months of June and July, where PS4 also has a stronger release line-up (if TLOU releases in June/July, which is likely).
Edit: Soz for the formatting of that, was written on phone.
