Interface. To improve the image.
Do you now, how the typical user chooses applications, like Antivirus? Interface. They look at the interface. And it is amazing (for users), when interface changes every few versions. User see of first sight that a program was changed. But F-Secure has this same interface since 2010 version (except for small details). Users interest unfortunately may fall...
I know, that F-Secure has really simply, clean and nice interface, but interface change (notiecable, NOT BIG) may have a positive impact on interest of program. Users will se - "Renewed, clean simply interface for a simply use" and... shed on the program