Changing brake levers on many road bikes is, in many cases, also changing the shifters, since most modern road bikes have integrated shift/brake levers ("brifters"). Many of them are slightly different in the way they are operated, or the number of cogs they will shift. For example, when changing from an 8 speed cassette to a ten speed cassette, one would be required to use a different shifter/brake lever that would handle the new gearing. That would be the only reason I could think of for changing levers, unless you just didn't like the name that was on the old ones..........