In 2.9 we use the transaction tab on a daily basis in the membership department and in the finance department. It is necessary for customer service, and to maintain the integrity of the membership data. We need a simple place to see what is happening without having to do research. The research comes later when a customer is on the phone or when a data analyst needs something fixed.
Here is an example - Mary Smith joined at the Annual Single level (1). When renewing the next year she adds her spouse(2). The next year she does not renew. The next year she rejoins at an Annual Single level(3), but her spouse is left off again, so we change it to Annual Family(4). Then she upgrades to Bronze Family (5), the next year to Silver Family (6). But she gets divorced, so I change the membership to Silver Single (7). The she renews and upgrades to Gold (8).
If all I can see is a level that say Gold Single how can I tell if it was ever a family membership without digging deeper? The single/family issue comes up ALL the time.
Visible on 2.9 Transaction Tab Only what has a double X in front of it below shows on 4.0membership page. To get to the detail readily visible now on transaction tab, you have to click on the membership level.

Annual (1) $50
XX-Annual Family (2) $ 0
Annual (3) $50
Annual Family (4) $ 0
Bronze Family (5) $100
Silver Family (6) $250
Silver (7) $0
XX-Gold (8) $500