The components of the DJIA have changed 53 times only in its 128-year history.
The same situation is with a lot of other market indices.
If we use top 100 market cap coins it will not show how much an investor will gain in % and he would need to change his portfolio every day.
It's not a long term investor approach.
Lazy? We all are lazy. You are lazy to look at http://alt19.com/marketindexes.html before quoting outdated info.
If I would use the approach you talk about, I'd just get Total Market Cap of 100 top coins from coinmarketcap.com and would make 'Altcoin index', based on this value.
It's very simple technically but it's not correct approach. It's really worthless for investors.
Interesting new coins... If I could short them it would be interesting... But as I have no this possibility and I'm not a miner...
Please tell me exactly which new interesting coins you mean, I will make their index and let's see where it will be an year later.
Because you are too lazy to develop a "rolling index" that would actually track the Alt Market.
All market indices remove stocks every month... and add stocks every month...
Also, you obviously do not trade interesting new coins... where all the action is.