I always get the details too (and load it into a spreadsheet).  Sometimes it's not needed but when it is, it's *really* nice to have a good history.  My worst horror story (several years ago now), client had ISO, ESPP and NQSO from his employer (all in different accounts).  Employer got bought out by another company and all of the swapped shares ended up getting dumped into the one account at a new broker.  New broker had no basis data.  So we were able to sort back through all of his exercise reports (fortunately he kept meticulous records) and establish basis for everything then translate old company basis into new company basis, then figure new company gain/loss.  This was a massive undertaking but the dollar amounts were well into the six-figures.

Lately it's been useful to have the data in a spreadsheet to deal with wash sale adjustments.

So, unless your clients are doing same-day sales, at some point you're going to want basis info.  Sometimes the brokers keep good records on this but sometimes I have to make adjustments.

Rick