The other reason for a new model is that when they cease making an old version they will save $ repairing the old models for free which are no longer produced. The Fluke "Lifetime" guarantee has an end clock which starts ticking when productions stops. (below)
"Industrial products limited Lifetime Warranty
Lifetime is defined as seven years after Fluke discontinues manufacturing the product, but the warranty period shall be at least ten years from date of purchase. *(Lifetime Warranty applies to products manufactured after October 1996). The warranty does not cover manuals, fuses, disposable batteries, damage from neglect, misuse, contamination, alteration, accident or abnormal conditions of operation or handling, including failures caused by use outside of the product's specifications, or normal wear and tear of mechanical components. This warranty covers the original purchaser only and is not transferable. This warranty covers the LCD for 10 years only (state-of-the-art for LCDs). To establish original ownership proof of purchase is required (20, 70, 80, 170, 180 and 280 models). THE FOLLOWING PRODUCTS ARE INTENDED FOR SALE AND USE IN THE CHINESE AND HIGH GROWTH MARKETS ONLY AND AVAILABLE FOR WARRANTY PROTECTION ONLY IF SOLD, PURCHASED AND USED SOLELY FROM AN AUTHORIZED DISTRIBUTOR WITHIN THESE TERRITORIES: 101, 106, 107, 15B+, 17B+ and 18B+. THE WARRANTY FOR THESE PRODUCTS IS VOID IF THE PRODUCT IS SOLD, PURCHASED OR USED OUTSIDE OF THESE TERRITORIES, OR FROM UNAUTHORIZED DISTRIBUTORS AND NO WARRANTY COVERAGE, SERVICE, REPAIR OR REPLACEMENT WILL BE PROVIDED."