@lovelygrace Well, Small Cap premium and such analyses involve usually the US market data, but for me it's important to capture mid-cap companies in emerging and/or other small markets where a 'mid-cap' is much smaller than the USD-Market cap definition and ends up falling under small-cap (i.e., quite big in those markets but not big by index standards).
For example, in India, the Nifty 500 index is comprised of 250 small cap, 150 mid cap, and 100 large-cap companies. However, the FTSE All-World index only has 171 companies from India in total. An All-Cap Index would stretch that number considerably to 268
after ESG exclusions, making sure the mid-cap is appropriately covered.
This effect is in-fact even present in bigger markets, where the index definition of mid-cap doesn't align with the country's popular local indices defining mid-cap. E.g. in Germany, DAX + MDAX = 90 companies only on the Prime Standard (i.e., General Standard is excluded), but FTSE All-World has only 81 while including both Prime and General Standard companies.
Personally, I am glad I can get exposure to global "small" cap companies while being able to exclude weapons manufacturers and coal energy companies, which otherwise seems impossible.
It would be good if an ETF in the future used more market-relevant definitions for large, mid, and small cap rather than a one-size fits all approach, but for now, this is what we have.