there's nothing wrong in having ethereum for the sake of gas fee and accumulating it.
I think its even recommended to invest in ethereum so you can just also accumulate and invest it, adding it to your holding portfolio will definitely increase the chance of making profit.
after all ethereum is among the most recommended altcoin to invest.
and i bet, eth will have market value after a year or two, as compared to most of his tokens. so yeah, it is better to stash some ETH not only for gas fees but as an investment as well. remember, it is top 2 among thousands of these currencies. so you have better chance of gaining profit from this project rather than most.