I have forwarded this feature request to the Product Manager.
However the reason that you can only hold 180 days is due to a sizing issue in the database. Here is a short explaination of what happens to the data in your database.
The data that is polled for the detailed data is polled every 10 minutes / 120 seconds by default (this can be changed on the system). This means that for every hour for each element there are 6 data points - 1hour/10 minutes. so for 24 hours that means that you have 144 datapoints in your database - 6 datapoints * 24.
If you are storing your data for 180 days on the 180th day, the detailed data is summarized into hourly data and is kept for 30 days by default.
The problem here happens when summarizing the data. If there is too much data then the database maintenance could fail and you could end up with your database growing very large.
I understand the explaination, but only having daily data after 180 days really washes out the data and trending spikes. I am not looking to keep the detailed as long. I would rather have the detailed data for something like 90 days and have the hourly for a year.
Maybe the system could validate some calc for the two detailed+hourly to allow for some flebibility. The more detailed the less the hour you can have vs less detailed would allow more hourly.