Thank you Sam2 for reminding everyone how knowledgeable Rav Schachter shlita is, and what a lack of Kovod haToroh it is to say anything against this Odom Godol. I 2nd motion your remarks Sam2.
As far as why many utilize Horseraddish, it is because Morror biZeman haZeh is mideRabbonon, whereas eating even 1 minifestle insect is a Biblical prohibition, and Horseraddish is probably less tricky to clean out than is say Romaine lettuce.