I can see how the information can be useful from a big-data perspective (finding correlations between the data of thousands of people), but for individuals I'm not convinced yet. For example, how do you know if a spike in BP is normal, or if it's only happening in your specific case and it needs attention?
I think the best answer to that is ask your doctor if you see something that concerns you. Though, even without an expert opinion or big data as a reference, establishing what is a baseline for yourself and then noting when there is significant deviation can have value. It could be an early warning sign or just encouragement to get help if your BP is one day very high or low. Some googling can probably give you an idea of what are normal ranges based on activity, too.
