Most Unit Trusts have 3 issues where seasoned investors dislike in general.
1. High management fee. 2% annual fee might sound small, but consider average annual return of 8%, 2% is effectively 25% of your profit being taken by the Trust management while you bear all the risk.
2. Lack of transparency. Yes you get the breakdown of the assets the Trust owns every month, but the way, timing and method of how the funds are being used are not disclosed in general... and yes they will give you a 170++ pages of prospectus to explain to you mostly useless stuff and hide the key facts in a sentence investors will tend to overlook.
3. Inability to claim back your investment in a timely manner. In stock if you sell your holdings you get your money within a week at most. Unit Trust the redeem process can take up to a month or longer, this is highly unfavorable when crisis struck.