You keep saying a license is a license, but in this case it's not entirely true.
Lifetime license included access to upgrades and technical support
Perpetual license included access to upgrades and then you had to pay $30/yr for technical support
Standard license requires $25 every 6 months to retain access to upgrades and technical support and also includes new services that IPS may offer in the future. Basically the costs of those services are factored into that $25 you pay every 6 months.
Lifetime license holders are not paying anything more, ever, so you are getting updates and new versions without IPS getting any compensation for their continued development.
Perpetual license holders only pay for technical support, which in most cases isn't needed, though some pay the fee just to support IPS.
Standard license holders are paying $25 every 6 months, which supports these new services that IPS deems suitable and cost effective (they wouldn't include a service where they would be spending more than what they are getting in for example).
It doesn't get any simpler than that. Hope you can understand now.